Remove //net (except for Android test stuff) and sdch

net/http/http_cache_transaction.cc

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "net/http/http_cache_transaction.h"
-
-#include "build/build_config.h"
-
-#if defined(OS_POSIX)
-#include <unistd.h>
-#endif
-
-#include <algorithm>
-#include <string>
-
-#include "base/bind.h"
-#include "base/compiler_specific.h"
-#include "base/format_macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/metrics/field_trial.h"
-#include "base/metrics/histogram.h"
-#include "base/metrics/sparse_histogram.h"
-#include "base/profiler/scoped_tracker.h"
-#include "base/rand_util.h"
-#include "base/strings/string_number_conversions.h"
-#include "base/strings/string_piece.h"
-#include "base/strings/string_util.h"
-#include "base/strings/stringprintf.h"
-#include "base/time/clock.h"
-#include "base/time/time.h"
-#include "base/values.h"
-#include "net/base/completion_callback.h"
-#include "net/base/io_buffer.h"
-#include "net/base/load_flags.h"
-#include "net/base/load_timing_info.h"
-#include "net/base/net_errors.h"
-#include "net/base/net_log.h"
-#include "net/base/upload_data_stream.h"
-#include "net/cert/cert_status_flags.h"
-#include "net/disk_cache/disk_cache.h"
-#include "net/http/disk_based_cert_cache.h"
-#include "net/http/http_network_session.h"
-#include "net/http/http_request_info.h"
-#include "net/http/http_response_headers.h"
-#include "net/http/http_transaction.h"
-#include "net/http/http_util.h"
-#include "net/http/partial_data.h"
-#include "net/ssl/ssl_cert_request_info.h"
-#include "net/ssl/ssl_config_service.h"
-
-using base::Time;
-using base::TimeDelta;
-using base::TimeTicks;
-
-namespace {
-
-// TODO(ricea): Move this to HttpResponseHeaders once it is standardised.
-static const char kFreshnessHeader[] = "Resource-Freshness";
-
-// Stores data relevant to the statistics of writing and reading entire
-// certificate chains using DiskBasedCertCache. |num_pending_ops| is the number
-// of certificates in the chain that have pending operations in the
-// DiskBasedCertCache. |start_time| is the time that the read and write
-// commands began being issued to the DiskBasedCertCache.
-// TODO(brandonsalmon): Remove this when it is no longer necessary to
-// collect data.
-class SharedChainData : public base::RefCounted<SharedChainData> {
- public:
-  SharedChainData(int num_ops, TimeTicks start)
-      : num_pending_ops(num_ops), start_time(start) {}
-
-  int num_pending_ops;
-  TimeTicks start_time;
-
- private:
-  friend class base::RefCounted<SharedChainData>;
-  ~SharedChainData() {}
-  DISALLOW_COPY_AND_ASSIGN(SharedChainData);
-};
-
-// Used to obtain a cache entry key for an OSCertHandle.
-// TODO(brandonsalmon): Remove this when cache keys are stored
-// and no longer have to be recomputed to retrieve the OSCertHandle
-// from the disk.
-std::string GetCacheKeyForCert(net::X509Certificate::OSCertHandle cert_handle) {
-  net::SHA1HashValue fingerprint =
-      net::X509Certificate::CalculateFingerprint(cert_handle);
-
-  return "cert:" +
-         base::HexEncode(fingerprint.data, arraysize(fingerprint.data));
-}
-
-// |dist_from_root| indicates the position of the read certificate in the
-// certificate chain, 0 indicating it is the root. |is_leaf| indicates
-// whether or not the read certificate was the leaf of the chain.
-// |shared_chain_data| contains data shared by each certificate in
-// the chain.
-void OnCertReadIOComplete(
-    int dist_from_root,
-    bool is_leaf,
-    const scoped_refptr<SharedChainData>& shared_chain_data,
-    net::X509Certificate::OSCertHandle cert_handle) {
-  // If |num_pending_ops| is one, this was the last pending read operation
-  // for this chain of certificates. The total time used to read the chain
-  // can be calculated by subtracting the starting time from Now().
-  shared_chain_data->num_pending_ops--;
-  if (!shared_chain_data->num_pending_ops) {
-    const TimeDelta read_chain_wait =
-        TimeTicks::Now() - shared_chain_data->start_time;
-    UMA_HISTOGRAM_CUSTOM_TIMES("DiskBasedCertCache.ChainReadTime",
-                               read_chain_wait,
-                               base::TimeDelta::FromMilliseconds(1),
-                               base::TimeDelta::FromMinutes(10),
-                               50);
-  }
-
-  bool success = (cert_handle != NULL);
-  if (is_leaf)
-    UMA_HISTOGRAM_BOOLEAN("DiskBasedCertCache.CertIoReadSuccessLeaf", success);
-
-  if (success)
-    UMA_HISTOGRAM_CUSTOM_COUNTS(
-        "DiskBasedCertCache.CertIoReadSuccess", dist_from_root, 0, 10, 7);
-  else
-    UMA_HISTOGRAM_CUSTOM_COUNTS(
-        "DiskBasedCertCache.CertIoReadFailure", dist_from_root, 0, 10, 7);
-}
-
-// |dist_from_root| indicates the position of the written certificate in the
-// certificate chain, 0 indicating it is the root. |is_leaf| indicates
-// whether or not the written certificate was the leaf of the chain.
-// |shared_chain_data| contains data shared by each certificate in
-// the chain.
-void OnCertWriteIOComplete(
-    int dist_from_root,
-    bool is_leaf,
-    const scoped_refptr<SharedChainData>& shared_chain_data,
-    const std::string& key) {
-  // If |num_pending_ops| is one, this was the last pending write operation
-  // for this chain of certificates. The total time used to write the chain
-  // can be calculated by subtracting the starting time from Now().
-  shared_chain_data->num_pending_ops--;
-  if (!shared_chain_data->num_pending_ops) {
-    const TimeDelta write_chain_wait =
-        TimeTicks::Now() - shared_chain_data->start_time;
-    UMA_HISTOGRAM_CUSTOM_TIMES("DiskBasedCertCache.ChainWriteTime",
-                               write_chain_wait,
-                               base::TimeDelta::FromMilliseconds(1),
-                               base::TimeDelta::FromMinutes(10),
-                               50);
-  }
-
-  bool success = !key.empty();
-  if (is_leaf)
-    UMA_HISTOGRAM_BOOLEAN("DiskBasedCertCache.CertIoWriteSuccessLeaf", success);
-
-  if (success)
-    UMA_HISTOGRAM_CUSTOM_COUNTS(
-        "DiskBasedCertCache.CertIoWriteSuccess", dist_from_root, 0, 10, 7);
-  else
-    UMA_HISTOGRAM_CUSTOM_COUNTS(
-        "DiskBasedCertCache.CertIoWriteFailure", dist_from_root, 0, 10, 7);
-}
-
-// From http://tools.ietf.org/html/draft-ietf-httpbis-p6-cache-21#section-6
-//      a "non-error response" is one with a 2xx (Successful) or 3xx
-//      (Redirection) status code.
-bool NonErrorResponse(int status_code) {
-  int status_code_range = status_code / 100;
-  return status_code_range == 2 || status_code_range == 3;
-}
-
-// Error codes that will be considered indicative of a page being offline/
-// unreachable for LOAD_FROM_CACHE_IF_OFFLINE.
-bool IsOfflineError(int error) {
-  return (error == net::ERR_NAME_NOT_RESOLVED ||
-          error == net::ERR_INTERNET_DISCONNECTED ||
-          error == net::ERR_ADDRESS_UNREACHABLE ||
-          error == net::ERR_CONNECTION_TIMED_OUT);
-}
-
-// Enum for UMA, indicating the status (with regard to offline mode) of
-// a particular request.
-enum RequestOfflineStatus {
-  // A cache transaction hit in cache (data was present and not stale)
-  // and returned it.
-  OFFLINE_STATUS_FRESH_CACHE,
-
-  // A network request was required for a cache entry, and it succeeded.
-  OFFLINE_STATUS_NETWORK_SUCCEEDED,
-
-  // A network request was required for a cache entry, and it failed with
-  // a non-offline error.
-  OFFLINE_STATUS_NETWORK_FAILED,
-
-  // A network request was required for a cache entry, it failed with an
-  // offline error, and we could serve stale data if
-  // LOAD_FROM_CACHE_IF_OFFLINE was set.
-  OFFLINE_STATUS_DATA_AVAILABLE_OFFLINE,
-
-  // A network request was required for a cache entry, it failed with
-  // an offline error, and there was no servable data in cache (even
-  // stale data).
-  OFFLINE_STATUS_DATA_UNAVAILABLE_OFFLINE,
-
-  OFFLINE_STATUS_MAX_ENTRIES
-};
-
-void RecordOfflineStatus(int load_flags, RequestOfflineStatus status) {
-  // Restrict to main frame to keep statistics close to
-  // "would have shown them something useful if offline mode was enabled".
-  if (load_flags & net::LOAD_MAIN_FRAME) {
-    UMA_HISTOGRAM_ENUMERATION("HttpCache.OfflineStatus", status,
-                              OFFLINE_STATUS_MAX_ENTRIES);
-  }
-}
-
-void RecordNoStoreHeaderHistogram(int load_flags,
-                                  const net::HttpResponseInfo* response) {
-  if (load_flags & net::LOAD_MAIN_FRAME) {
-    UMA_HISTOGRAM_BOOLEAN(
-        "Net.MainFrameNoStore",
-        response->headers->HasHeaderValue("cache-control", "no-store"));
-  }
-}
-
-base::Value* NetLogAsyncRevalidationInfoCallback(
-    const net::NetLog::Source& source,
-    const net::HttpRequestInfo* request,
-    net::NetLog::LogLevel log_level) {
-  base::DictionaryValue* dict = new base::DictionaryValue();
-  source.AddToEventParameters(dict);
-
-  dict->SetString("url", request->url.possibly_invalid_spec());
-  dict->SetString("method", request->method);
-  return dict;
-}
-
-enum ExternallyConditionalizedType {
-  EXTERNALLY_CONDITIONALIZED_CACHE_REQUIRES_VALIDATION,
-  EXTERNALLY_CONDITIONALIZED_CACHE_USABLE,
-  EXTERNALLY_CONDITIONALIZED_MISMATCHED_VALIDATORS,
-  EXTERNALLY_CONDITIONALIZED_MAX
-};
-
-}  // namespace
-
-namespace net {
-
-struct HeaderNameAndValue {
-  const char* name;
-  const char* value;
-};
-
-// If the request includes one of these request headers, then avoid caching
-// to avoid getting confused.
-static const HeaderNameAndValue kPassThroughHeaders[] = {
-  { "if-unmodified-since", NULL },  // causes unexpected 412s
-  { "if-match", NULL },             // causes unexpected 412s
-  { "if-range", NULL },
-  { NULL, NULL }
-};
-
-struct ValidationHeaderInfo {
-  const char* request_header_name;
-  const char* related_response_header_name;
-};
-
-static const ValidationHeaderInfo kValidationHeaders[] = {
-  { "if-modified-since", "last-modified" },
-  { "if-none-match", "etag" },
-};
-
-// If the request includes one of these request headers, then avoid reusing
-// our cached copy if any.
-static const HeaderNameAndValue kForceFetchHeaders[] = {
-  { "cache-control", "no-cache" },
-  { "pragma", "no-cache" },
-  { NULL, NULL }
-};
-
-// If the request includes one of these request headers, then force our
-// cached copy (if any) to be revalidated before reusing it.
-static const HeaderNameAndValue kForceValidateHeaders[] = {
-  { "cache-control", "max-age=0" },
-  { NULL, NULL }
-};
-
-static bool HeaderMatches(const HttpRequestHeaders& headers,
-                          const HeaderNameAndValue* search) {
-  for (; search->name; ++search) {
-    std::string header_value;
-    if (!headers.GetHeader(search->name, &header_value))
-      continue;
-
-    if (!search->value)
-      return true;
-
-    HttpUtil::ValuesIterator v(header_value.begin(), header_value.end(), ',');
-    while (v.GetNext()) {
-      if (LowerCaseEqualsASCII(v.value_begin(), v.value_end(), search->value))
-        return true;
-    }
-  }
-  return false;
-}
-
-//-----------------------------------------------------------------------------
-
-HttpCache::Transaction::Transaction(RequestPriority priority, HttpCache* cache)
-    : next_state_(STATE_NONE),
-      request_(NULL),
-      priority_(priority),
-      cache_(cache->GetWeakPtr()),
-      entry_(NULL),
-      new_entry_(NULL),
-      new_response_(NULL),
-      mode_(NONE),
-      target_state_(STATE_NONE),
-      reading_(false),
-      invalid_range_(false),
-      truncated_(false),
-      is_sparse_(false),
-      range_requested_(false),
-      handling_206_(false),
-      cache_pending_(false),
-      done_reading_(false),
-      vary_mismatch_(false),
-      couldnt_conditionalize_request_(false),
-      bypass_lock_for_test_(false),
-      fail_conditionalization_for_test_(false),
-      io_buf_len_(0),
-      read_offset_(0),
-      effective_load_flags_(0),
-      write_len_(0),
-      transaction_pattern_(PATTERN_UNDEFINED),
-      total_received_bytes_(0),
-      websocket_handshake_stream_base_create_helper_(NULL),
-      weak_factory_(this) {
-  static_assert(HttpCache::Transaction::kNumValidationHeaders ==
-                    arraysize(kValidationHeaders),
-                "invalid number of validation headers");
-
-  io_callback_ = base::Bind(&Transaction::OnIOComplete,
-                              weak_factory_.GetWeakPtr());
-}
-
-HttpCache::Transaction::~Transaction() {
-  // We may have to issue another IO, but we should never invoke the callback_
-  // after this point.
-  callback_.Reset();
-
-  if (cache_) {
-    if (entry_) {
-      bool cancel_request = reading_ && response_.headers.get();
-      if (cancel_request) {
-        if (partial_) {
-          entry_->disk_entry->CancelSparseIO();
-        } else {
-          cancel_request &= (response_.headers->response_code() == 200);
-        }
-      }
-
-      cache_->DoneWithEntry(entry_, this, cancel_request);
-    } else if (cache_pending_) {
-      cache_->RemovePendingTransaction(this);
-    }
-  }
-}
-
-int HttpCache::Transaction::WriteMetadata(IOBuffer* buf, int buf_len,
-                                          const CompletionCallback& callback) {
-  DCHECK(buf);
-  DCHECK_GT(buf_len, 0);
-  DCHECK(!callback.is_null());
-  if (!cache_.get() || !entry_)
-    return ERR_UNEXPECTED;
-
-  // We don't need to track this operation for anything.
-  // It could be possible to check if there is something already written and
-  // avoid writing again (it should be the same, right?), but let's allow the
-  // caller to "update" the contents with something new.
-  return entry_->disk_entry->WriteData(kMetadataIndex, 0, buf, buf_len,
-                                       callback, true);
-}
-
-bool HttpCache::Transaction::AddTruncatedFlag() {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-
-  // Don't set the flag for sparse entries.
-  if (partial_.get() && !truncated_)
-    return true;
-
-  if (!CanResume(true))
-    return false;
-
-  // We may have received the whole resource already.
-  if (done_reading_)
-    return true;
-
-  truncated_ = true;
-  target_state_ = STATE_NONE;
-  next_state_ = STATE_CACHE_WRITE_TRUNCATED_RESPONSE;
-  DoLoop(OK);
-  return true;
-}
-
-LoadState HttpCache::Transaction::GetWriterLoadState() const {
-  if (network_trans_.get())
-    return network_trans_->GetLoadState();
-  if (entry_ || !request_)
-    return LOAD_STATE_IDLE;
-  return LOAD_STATE_WAITING_FOR_CACHE;
-}
-
-const BoundNetLog& HttpCache::Transaction::net_log() const {
-  return net_log_;
-}
-
-int HttpCache::Transaction::Start(const HttpRequestInfo* request,
-                                  const CompletionCallback& callback,
-                                  const BoundNetLog& net_log) {
-  DCHECK(request);
-  DCHECK(!callback.is_null());
-
-  // Ensure that we only have one asynchronous call at a time.
-  DCHECK(callback_.is_null());
-  DCHECK(!reading_);
-  DCHECK(!network_trans_.get());
-  DCHECK(!entry_);
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  SetRequest(net_log, request);
-
-  // We have to wait until the backend is initialized so we start the SM.
-  next_state_ = STATE_GET_BACKEND;
-  int rv = DoLoop(OK);
-
-  // Setting this here allows us to check for the existence of a callback_ to
-  // determine if we are still inside Start.
-  if (rv == ERR_IO_PENDING) {
-    callback_ = tracked_objects::ScopedTracker::TrackCallback(
-        FROM_HERE_WITH_EXPLICIT_FUNCTION(
-            "422516 HttpCache::Transaction::Start"),
-        callback);
-  }
-
-  return rv;
-}
-
-int HttpCache::Transaction::RestartIgnoringLastError(
-    const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-
-  // Ensure that we only have one asynchronous call at a time.
-  DCHECK(callback_.is_null());
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  int rv = RestartNetworkRequest();
-
-  if (rv == ERR_IO_PENDING) {
-    callback_ = tracked_objects::ScopedTracker::TrackCallback(
-        FROM_HERE_WITH_EXPLICIT_FUNCTION(
-            "422516 HttpCache::Transaction::RestartIgnoringLastError"),
-        callback);
-  }
-
-  return rv;
-}
-
-int HttpCache::Transaction::RestartWithCertificate(
-    X509Certificate* client_cert,
-    const CompletionCallback& callback) {
-  DCHECK(!callback.is_null());
-
-  // Ensure that we only have one asynchronous call at a time.
-  DCHECK(callback_.is_null());
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  int rv = RestartNetworkRequestWithCertificate(client_cert);
-
-  if (rv == ERR_IO_PENDING) {
-    callback_ = tracked_objects::ScopedTracker::TrackCallback(
-        FROM_HERE_WITH_EXPLICIT_FUNCTION(
-            "422516 HttpCache::Transaction::RestartWithCertificate"),
-        callback);
-  }
-
-  return rv;
-}
-
-int HttpCache::Transaction::RestartWithAuth(
-    const AuthCredentials& credentials,
-    const CompletionCallback& callback) {
-  DCHECK(auth_response_.headers.get());
-  DCHECK(!callback.is_null());
-
-  // Ensure that we only have one asynchronous call at a time.
-  DCHECK(callback_.is_null());
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  // Clear the intermediate response since we are going to start over.
-  auth_response_ = HttpResponseInfo();
-
-  int rv = RestartNetworkRequestWithAuth(credentials);
-
-  if (rv == ERR_IO_PENDING) {
-    callback_ = tracked_objects::ScopedTracker::TrackCallback(
-        FROM_HERE_WITH_EXPLICIT_FUNCTION(
-            "422516 HttpCache::Transaction::RestartWithAuth"),
-        callback);
-  }
-
-  return rv;
-}
-
-bool HttpCache::Transaction::IsReadyToRestartForAuth() {
-  if (!network_trans_.get())
-    return false;
-  return network_trans_->IsReadyToRestartForAuth();
-}
-
-int HttpCache::Transaction::Read(IOBuffer* buf, int buf_len,
-                                 const CompletionCallback& callback) {
-  DCHECK(buf);
-  DCHECK_GT(buf_len, 0);
-  DCHECK(!callback.is_null());
-
-  DCHECK(callback_.is_null());
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  // If we have an intermediate auth response at this point, then it means the
-  // user wishes to read the network response (the error page).  If there is a
-  // previous response in the cache then we should leave it intact.
-  if (auth_response_.headers.get() && mode_ != NONE) {
-    UpdateTransactionPattern(PATTERN_NOT_COVERED);
-    DCHECK(mode_ & WRITE);
-    DoneWritingToEntry(mode_ == READ_WRITE);
-    mode_ = NONE;
-  }
-
-  reading_ = true;
-  int rv;
-
-  switch (mode_) {
-    case READ_WRITE:
-      DCHECK(partial_.get());
-      if (!network_trans_.get()) {
-        // We are just reading from the cache, but we may be writing later.
-        rv = ReadFromEntry(buf, buf_len);
-        break;
-      }
-    case NONE:
-    case WRITE:
-      DCHECK(network_trans_.get());
-      rv = ReadFromNetwork(buf, buf_len);
-      break;
-    case READ:
-      rv = ReadFromEntry(buf, buf_len);
-      break;
-    default:
-      NOTREACHED();
-      rv = ERR_FAILED;
-  }
-
-  if (rv == ERR_IO_PENDING) {
-    DCHECK(callback_.is_null());
-    callback_ = tracked_objects::ScopedTracker::TrackCallback(
-        FROM_HERE_WITH_EXPLICIT_FUNCTION("422516 HttpCache::Transaction::Read"),
-        callback);
-  }
-  return rv;
-}
-
-void HttpCache::Transaction::StopCaching() {
-  // We really don't know where we are now. Hopefully there is no operation in
-  // progress, but nothing really prevents this method to be called after we
-  // returned ERR_IO_PENDING. We cannot attempt to truncate the entry at this
-  // point because we need the state machine for that (and even if we are really
-  // free, that would be an asynchronous operation). In other words, keep the
-  // entry how it is (it will be marked as truncated at destruction), and let
-  // the next piece of code that executes know that we are now reading directly
-  // from the net.
-  // TODO(mmenke):  This doesn't release the lock on the cache entry, so a
-  //                future request for the resource will be blocked on this one.
-  //                Fix this.
-  if (cache_.get() && entry_ && (mode_ & WRITE) && network_trans_.get() &&
-      !is_sparse_ && !range_requested_) {
-    mode_ = NONE;
-  }
-}
-
-bool HttpCache::Transaction::GetFullRequestHeaders(
-    HttpRequestHeaders* headers) const {
-  if (network_trans_)
-    return network_trans_->GetFullRequestHeaders(headers);
-
-  // TODO(ttuttle): Read headers from cache.
-  return false;
-}
-
-int64 HttpCache::Transaction::GetTotalReceivedBytes() const {
-  int64 total_received_bytes = total_received_bytes_;
-  if (network_trans_)
-    total_received_bytes += network_trans_->GetTotalReceivedBytes();
-  return total_received_bytes;
-}
-
-void HttpCache::Transaction::DoneReading() {
-  if (cache_.get() && entry_) {
-    DCHECK_NE(mode_, UPDATE);
-    if (mode_ & WRITE) {
-      DoneWritingToEntry(true);
-    } else if (mode_ & READ) {
-      // It is necessary to check mode_ & READ because it is possible
-      // for mode_ to be NONE and entry_ non-NULL with a write entry
-      // if StopCaching was called.
-      cache_->DoneReadingFromEntry(entry_, this);
-      entry_ = NULL;
-    }
-  }
-}
-
-const HttpResponseInfo* HttpCache::Transaction::GetResponseInfo() const {
-  // Null headers means we encountered an error or haven't a response yet
-  if (auth_response_.headers.get())
-    return &auth_response_;
-  return (response_.headers.get() || response_.ssl_info.cert.get() ||
-          response_.cert_request_info.get())
-             ? &response_
-             : NULL;
-}
-
-LoadState HttpCache::Transaction::GetLoadState() const {
-  LoadState state = GetWriterLoadState();
-  if (state != LOAD_STATE_WAITING_FOR_CACHE)
-    return state;
-
-  if (cache_.get())
-    return cache_->GetLoadStateForPendingTransaction(this);
-
-  return LOAD_STATE_IDLE;
-}
-
-UploadProgress HttpCache::Transaction::GetUploadProgress() const {
-  if (network_trans_.get())
-    return network_trans_->GetUploadProgress();
-  return final_upload_progress_;
-}
-
-void HttpCache::Transaction::SetQuicServerInfo(
-    QuicServerInfo* quic_server_info) {}
-
-bool HttpCache::Transaction::GetLoadTimingInfo(
-    LoadTimingInfo* load_timing_info) const {
-  if (network_trans_)
-    return network_trans_->GetLoadTimingInfo(load_timing_info);
-
-  if (old_network_trans_load_timing_) {
-    *load_timing_info = *old_network_trans_load_timing_;
-    return true;
-  }
-
-  if (first_cache_access_since_.is_null())
-    return false;
-
-  // If the cache entry was opened, return that time.
-  load_timing_info->send_start = first_cache_access_since_;
-  // This time doesn't make much sense when reading from the cache, so just use
-  // the same time as send_start.
-  load_timing_info->send_end = first_cache_access_since_;
-  return true;
-}
-
-void HttpCache::Transaction::SetPriority(RequestPriority priority) {
-  priority_ = priority;
-  if (network_trans_)
-    network_trans_->SetPriority(priority_);
-}
-
-void HttpCache::Transaction::SetWebSocketHandshakeStreamCreateHelper(
-    WebSocketHandshakeStreamBase::CreateHelper* create_helper) {
-  websocket_handshake_stream_base_create_helper_ = create_helper;
-  if (network_trans_)
-    network_trans_->SetWebSocketHandshakeStreamCreateHelper(create_helper);
-}
-
-void HttpCache::Transaction::SetBeforeNetworkStartCallback(
-    const BeforeNetworkStartCallback& callback) {
-  DCHECK(!network_trans_);
-  before_network_start_callback_ = callback;
-}
-
-void HttpCache::Transaction::SetBeforeProxyHeadersSentCallback(
-    const BeforeProxyHeadersSentCallback& callback) {
-  DCHECK(!network_trans_);
-  before_proxy_headers_sent_callback_ = callback;
-}
-
-int HttpCache::Transaction::ResumeNetworkStart() {
-  if (network_trans_)
-    return network_trans_->ResumeNetworkStart();
-  return ERR_UNEXPECTED;
-}
-
-//-----------------------------------------------------------------------------
-
-void HttpCache::Transaction::DoCallback(int rv) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCallback"));
-
-  DCHECK(rv != ERR_IO_PENDING);
-  DCHECK(!callback_.is_null());
-
-  read_buf_ = NULL;  // Release the buffer before invoking the callback.
-
-  // Since Run may result in Read being called, clear callback_ up front.
-  CompletionCallback c = callback_;
-  callback_.Reset();
-  c.Run(rv);
-}
-
-int HttpCache::Transaction::HandleResult(int rv) {
-  DCHECK(rv != ERR_IO_PENDING);
-  if (!callback_.is_null())
-    DoCallback(rv);
-
-  return rv;
-}
-
-// A few common patterns: (Foo* means Foo -> FooComplete)
-//
-// 1. Not-cached entry:
-//   Start():
-//   GetBackend* -> InitEntry -> OpenEntry* -> CreateEntry* -> AddToEntry* ->
-//   SendRequest* -> SuccessfulSendRequest -> OverwriteCachedResponse ->
-//   CacheWriteResponse* -> TruncateCachedData* -> TruncateCachedMetadata* ->
-//   PartialHeadersReceived
-//
-//   Read():
-//   NetworkRead* -> CacheWriteData*
-//
-// 2. Cached entry, no validation:
-//   Start():
-//   GetBackend* -> InitEntry -> OpenEntry* -> AddToEntry* -> CacheReadResponse*
-//   -> CacheDispatchValidation -> BeginPartialCacheValidation() ->
-//   BeginCacheValidation() -> SetupEntryForRead()
-//
-//   Read():
-//   CacheReadData*
-//
-// 3. Cached entry, validation (304):
-//   Start():
-//   GetBackend* -> InitEntry -> OpenEntry* -> AddToEntry* -> CacheReadResponse*
-//   -> CacheDispatchValidation -> BeginPartialCacheValidation() ->
-//   BeginCacheValidation() -> SendRequest* -> SuccessfulSendRequest ->
-//   UpdateCachedResponse -> CacheWriteResponse* -> UpdateCachedResponseComplete
-//   -> OverwriteCachedResponse -> PartialHeadersReceived
-//
-//   Read():
-//   CacheReadData*
-//
-// 4. Cached entry, validation and replace (200):
-//   Start():
-//   GetBackend* -> InitEntry -> OpenEntry* -> AddToEntry* -> CacheReadResponse*
-//   -> CacheDispatchValidation -> BeginPartialCacheValidation() ->
-//   BeginCacheValidation() -> SendRequest* -> SuccessfulSendRequest ->
-//   OverwriteCachedResponse -> CacheWriteResponse* -> DoTruncateCachedData* ->
-//   TruncateCachedMetadata* -> PartialHeadersReceived
-//
-//   Read():
-//   NetworkRead* -> CacheWriteData*
-//
-// 5. Sparse entry, partially cached, byte range request:
-//   Start():
-//   GetBackend* -> InitEntry -> OpenEntry* -> AddToEntry* -> CacheReadResponse*
-//   -> CacheDispatchValidation -> BeginPartialCacheValidation() ->
-//   CacheQueryData* -> ValidateEntryHeadersAndContinue() ->
-//   StartPartialCacheValidation -> CompletePartialCacheValidation ->
-//   BeginCacheValidation() -> SendRequest* -> SuccessfulSendRequest ->
-//   UpdateCachedResponse -> CacheWriteResponse* -> UpdateCachedResponseComplete
-//   -> OverwriteCachedResponse -> PartialHeadersReceived
-//
-//   Read() 1:
-//   NetworkRead* -> CacheWriteData*
-//
-//   Read() 2:
-//   NetworkRead* -> CacheWriteData* -> StartPartialCacheValidation ->
-//   CompletePartialCacheValidation -> CacheReadData* ->
-//
-//   Read() 3:
-//   CacheReadData* -> StartPartialCacheValidation ->
-//   CompletePartialCacheValidation -> BeginCacheValidation() -> SendRequest* ->
-//   SuccessfulSendRequest -> UpdateCachedResponse* -> OverwriteCachedResponse
-//   -> PartialHeadersReceived -> NetworkRead* -> CacheWriteData*
-//
-// 6. HEAD. Not-cached entry:
-//   Pass through. Don't save a HEAD by itself.
-//   Start():
-//   GetBackend* -> InitEntry -> OpenEntry* -> SendRequest*
-//
-// 7. HEAD. Cached entry, no validation:
-//   Start():
-//   The same flow as for a GET request (example #2)
-//
-//   Read():
-//   CacheReadData (returns 0)
-//
-// 8. HEAD. Cached entry, validation (304):
-//   The request updates the stored headers.
-//   Start(): Same as for a GET request (example #3)
-//
-//   Read():
-//   CacheReadData (returns 0)
-//
-// 9. HEAD. Cached entry, validation and replace (200):
-//   Pass through. The request dooms the old entry, as a HEAD won't be stored by
-//   itself.
-//   Start():
-//   GetBackend* -> InitEntry -> OpenEntry* -> AddToEntry* -> CacheReadResponse*
-//   -> CacheDispatchValidation -> BeginPartialCacheValidation() ->
-//   BeginCacheValidation() -> SendRequest* -> SuccessfulSendRequest ->
-//   OverwriteCachedResponse
-//
-// 10. HEAD. Sparse entry, partially cached:
-//   Serve the request from the cache, as long as it doesn't require
-//   revalidation. Ignore missing ranges when deciding to revalidate. If the
-//   entry requires revalidation, ignore the whole request and go to full pass
-//   through (the result of the HEAD request will NOT update the entry).
-//
-//   Start(): Basically the same as example 7, as we never create a partial_
-//   object for this request.
-//
-// 11. Prefetch, not-cached entry:
-//   The same as example 1. The "unused_since_prefetch" bit is stored as true in
-//   UpdateCachedResponse.
-//
-// 12. Prefetch, cached entry:
-//   Like examples 2-4, only CacheToggleUnusedSincePrefetch* is inserted between
-//   CacheReadResponse* and CacheDispatchValidation if the unused_since_prefetch
-//   bit is unset.
-//
-// 13. Cached entry less than 5 minutes old, unused_since_prefetch is true:
-//   Skip validation, similar to example 2.
-//   GetBackend* -> InitEntry -> OpenEntry* -> AddToEntry* -> CacheReadResponse*
-//   -> CacheToggleUnusedSincePrefetch* -> CacheDispatchValidation ->
-//   BeginPartialCacheValidation() -> BeginCacheValidation() ->
-//   SetupEntryForRead()
-//
-//   Read():
-//   CacheReadData*
-//
-// 14. Cached entry more than 5 minutes old, unused_since_prefetch is true:
-//   Like examples 2-4, only CacheToggleUnusedSincePrefetch* is inserted between
-//   CacheReadResponse* and CacheDispatchValidation.
-int HttpCache::Transaction::DoLoop(int result) {
-  DCHECK(next_state_ != STATE_NONE);
-
-  int rv = result;
-  do {
-    State state = next_state_;
-    next_state_ = STATE_NONE;
-    switch (state) {
-      case STATE_GET_BACKEND:
-        DCHECK_EQ(OK, rv);
-        rv = DoGetBackend();
-        break;
-      case STATE_GET_BACKEND_COMPLETE:
-        rv = DoGetBackendComplete(rv);
-        break;
-      case STATE_SEND_REQUEST:
-        DCHECK_EQ(OK, rv);
-        rv = DoSendRequest();
-        break;
-      case STATE_SEND_REQUEST_COMPLETE:
-        rv = DoSendRequestComplete(rv);
-        break;
-      case STATE_SUCCESSFUL_SEND_REQUEST:
-        DCHECK_EQ(OK, rv);
-        rv = DoSuccessfulSendRequest();
-        break;
-      case STATE_NETWORK_READ:
-        DCHECK_EQ(OK, rv);
-        rv = DoNetworkRead();
-        break;
-      case STATE_NETWORK_READ_COMPLETE:
-        rv = DoNetworkReadComplete(rv);
-        break;
-      case STATE_INIT_ENTRY:
-        DCHECK_EQ(OK, rv);
-        rv = DoInitEntry();
-        break;
-      case STATE_OPEN_ENTRY:
-        DCHECK_EQ(OK, rv);
-        rv = DoOpenEntry();
-        break;
-      case STATE_OPEN_ENTRY_COMPLETE:
-        rv = DoOpenEntryComplete(rv);
-        break;
-      case STATE_CREATE_ENTRY:
-        DCHECK_EQ(OK, rv);
-        rv = DoCreateEntry();
-        break;
-      case STATE_CREATE_ENTRY_COMPLETE:
-        rv = DoCreateEntryComplete(rv);
-        break;
-      case STATE_DOOM_ENTRY:
-        DCHECK_EQ(OK, rv);
-        rv = DoDoomEntry();
-        break;
-      case STATE_DOOM_ENTRY_COMPLETE:
-        rv = DoDoomEntryComplete(rv);
-        break;
-      case STATE_ADD_TO_ENTRY:
-        DCHECK_EQ(OK, rv);
-        rv = DoAddToEntry();
-        break;
-      case STATE_ADD_TO_ENTRY_COMPLETE:
-        rv = DoAddToEntryComplete(rv);
-        break;
-      case STATE_START_PARTIAL_CACHE_VALIDATION:
-        DCHECK_EQ(OK, rv);
-        rv = DoStartPartialCacheValidation();
-        break;
-      case STATE_COMPLETE_PARTIAL_CACHE_VALIDATION:
-        rv = DoCompletePartialCacheValidation(rv);
-        break;
-      case STATE_UPDATE_CACHED_RESPONSE:
-        DCHECK_EQ(OK, rv);
-        rv = DoUpdateCachedResponse();
-        break;
-      case STATE_UPDATE_CACHED_RESPONSE_COMPLETE:
-        rv = DoUpdateCachedResponseComplete(rv);
-        break;
-      case STATE_OVERWRITE_CACHED_RESPONSE:
-        DCHECK_EQ(OK, rv);
-        rv = DoOverwriteCachedResponse();
-        break;
-      case STATE_TRUNCATE_CACHED_DATA:
-        DCHECK_EQ(OK, rv);
-        rv = DoTruncateCachedData();
-        break;
-      case STATE_TRUNCATE_CACHED_DATA_COMPLETE:
-        rv = DoTruncateCachedDataComplete(rv);
-        break;
-      case STATE_TRUNCATE_CACHED_METADATA:
-        DCHECK_EQ(OK, rv);
-        rv = DoTruncateCachedMetadata();
-        break;
-      case STATE_TRUNCATE_CACHED_METADATA_COMPLETE:
-        rv = DoTruncateCachedMetadataComplete(rv);
-        break;
-      case STATE_PARTIAL_HEADERS_RECEIVED:
-        DCHECK_EQ(OK, rv);
-        rv = DoPartialHeadersReceived();
-        break;
-      case STATE_CACHE_READ_RESPONSE:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheReadResponse();
-        break;
-      case STATE_CACHE_READ_RESPONSE_COMPLETE:
-        rv = DoCacheReadResponseComplete(rv);
-        break;
-      case STATE_CACHE_DISPATCH_VALIDATION:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheDispatchValidation();
-        break;
-      case STATE_TOGGLE_UNUSED_SINCE_PREFETCH:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheToggleUnusedSincePrefetch();
-        break;
-      case STATE_TOGGLE_UNUSED_SINCE_PREFETCH_COMPLETE:
-        rv = DoCacheToggleUnusedSincePrefetchComplete(rv);
-        break;
-      case STATE_CACHE_WRITE_RESPONSE:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheWriteResponse();
-        break;
-      case STATE_CACHE_WRITE_TRUNCATED_RESPONSE:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheWriteTruncatedResponse();
-        break;
-      case STATE_CACHE_WRITE_RESPONSE_COMPLETE:
-        rv = DoCacheWriteResponseComplete(rv);
-        break;
-      case STATE_CACHE_READ_METADATA:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheReadMetadata();
-        break;
-      case STATE_CACHE_READ_METADATA_COMPLETE:
-        rv = DoCacheReadMetadataComplete(rv);
-        break;
-      case STATE_CACHE_QUERY_DATA:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheQueryData();
-        break;
-      case STATE_CACHE_QUERY_DATA_COMPLETE:
-        rv = DoCacheQueryDataComplete(rv);
-        break;
-      case STATE_CACHE_READ_DATA:
-        DCHECK_EQ(OK, rv);
-        rv = DoCacheReadData();
-        break;
-      case STATE_CACHE_READ_DATA_COMPLETE:
-        rv = DoCacheReadDataComplete(rv);
-        break;
-      case STATE_CACHE_WRITE_DATA:
-        rv = DoCacheWriteData(rv);
-        break;
-      case STATE_CACHE_WRITE_DATA_COMPLETE:
-        rv = DoCacheWriteDataComplete(rv);
-        break;
-      default:
-        NOTREACHED() << "bad state";
-        rv = ERR_FAILED;
-        break;
-    }
-  } while (rv != ERR_IO_PENDING && next_state_ != STATE_NONE);
-
-  if (rv != ERR_IO_PENDING)
-    HandleResult(rv);
-
-  return rv;
-}
-
-int HttpCache::Transaction::DoGetBackend() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoGetBackend"));
-
-  cache_pending_ = true;
-  next_state_ = STATE_GET_BACKEND_COMPLETE;
-  net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_GET_BACKEND);
-  return cache_->GetBackendForTransaction(this);
-}
-
-int HttpCache::Transaction::DoGetBackendComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoGetBackendComplete"));
-
-  DCHECK(result == OK || result == ERR_FAILED);
-  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_GET_BACKEND,
-                                    result);
-  cache_pending_ = false;
-
-  if (!ShouldPassThrough()) {
-    cache_key_ = cache_->GenerateCacheKey(request_);
-
-    // Requested cache access mode.
-    if (effective_load_flags_ & LOAD_ONLY_FROM_CACHE) {
-      mode_ = READ;
-    } else if (effective_load_flags_ & LOAD_BYPASS_CACHE) {
-      mode_ = WRITE;
-    } else {
-      mode_ = READ_WRITE;
-    }
-
-    // Downgrade to UPDATE if the request has been externally conditionalized.
-    if (external_validation_.initialized) {
-      if (mode_ & WRITE) {
-        // Strip off the READ_DATA bit (and maybe add back a READ_META bit
-        // in case READ was off).
-        mode_ = UPDATE;
-      } else {
-        mode_ = NONE;
-      }
-    }
-  }
-
-  // Use PUT and DELETE only to invalidate existing stored entries.
-  if ((request_->method == "PUT" || request_->method == "DELETE") &&
-      mode_ != READ_WRITE && mode_ != WRITE) {
-    mode_ = NONE;
-  }
-
-  // Note that if mode_ == UPDATE (which is tied to external_validation_), the
-  // transaction behaves the same for GET and HEAD requests at this point: if it
-  // was not modified, the entry is updated and a response is not returned from
-  // the cache. If we receive 200, it doesn't matter if there was a validation
-  // header or not.
-  if (request_->method == "HEAD" && mode_ == WRITE)
-    mode_ = NONE;
-
-  // If must use cache, then we must fail.  This can happen for back/forward
-  // navigations to a page generated via a form post.
-  if (!(mode_ & READ) && effective_load_flags_ & LOAD_ONLY_FROM_CACHE)
-    return ERR_CACHE_MISS;
-
-  if (mode_ == NONE) {
-    if (partial_.get()) {
-      partial_->RestoreHeaders(&custom_request_->extra_headers);
-      partial_.reset();
-    }
-    next_state_ = STATE_SEND_REQUEST;
-  } else {
-    next_state_ = STATE_INIT_ENTRY;
-  }
-
-  // This is only set if we have something to do with the response.
-  range_requested_ = (partial_.get() != NULL);
-
-  return OK;
-}
-
-int HttpCache::Transaction::DoSendRequest() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoSendRequest"));
-
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(!network_trans_.get());
-
-  send_request_since_ = TimeTicks::Now();
-
-  // Create a network transaction.
-  int rv = cache_->network_layer_->CreateTransaction(priority_,
-                                                     &network_trans_);
-  if (rv != OK)
-    return rv;
-  network_trans_->SetBeforeNetworkStartCallback(before_network_start_callback_);
-  network_trans_->SetBeforeProxyHeadersSentCallback(
-      before_proxy_headers_sent_callback_);
-
-  // Old load timing information, if any, is now obsolete.
-  old_network_trans_load_timing_.reset();
-
-  if (websocket_handshake_stream_base_create_helper_)
-    network_trans_->SetWebSocketHandshakeStreamCreateHelper(
-        websocket_handshake_stream_base_create_helper_);
-
-  next_state_ = STATE_SEND_REQUEST_COMPLETE;
-  rv = network_trans_->Start(request_, io_callback_, net_log_);
-  return rv;
-}
-
-int HttpCache::Transaction::DoSendRequestComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoSendRequestComplete"));
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  // If requested, and we have a readable cache entry, and we have
-  // an error indicating that we're offline as opposed to in contact
-  // with a bad server, read from cache anyway.
-  if (IsOfflineError(result)) {
-    if (mode_ == READ_WRITE && entry_ && !partial_) {
-      RecordOfflineStatus(effective_load_flags_,
-                          OFFLINE_STATUS_DATA_AVAILABLE_OFFLINE);
-      if (effective_load_flags_ & LOAD_FROM_CACHE_IF_OFFLINE) {
-        UpdateTransactionPattern(PATTERN_NOT_COVERED);
-        response_.server_data_unavailable = true;
-        return SetupEntryForRead();
-      }
-    } else {
-      RecordOfflineStatus(effective_load_flags_,
-                          OFFLINE_STATUS_DATA_UNAVAILABLE_OFFLINE);
-    }
-  } else {
-    RecordOfflineStatus(effective_load_flags_,
-                        (result == OK ? OFFLINE_STATUS_NETWORK_SUCCEEDED :
-                                        OFFLINE_STATUS_NETWORK_FAILED));
-  }
-
-  // If we tried to conditionalize the request and failed, we know
-  // we won't be reading from the cache after this point.
-  if (couldnt_conditionalize_request_)
-    mode_ = WRITE;
-
-  if (result == OK) {
-    next_state_ = STATE_SUCCESSFUL_SEND_REQUEST;
-    return OK;
-  }
-
-  // Do not record requests that have network errors or restarts.
-  UpdateTransactionPattern(PATTERN_NOT_COVERED);
-  if (IsCertificateError(result)) {
-    const HttpResponseInfo* response = network_trans_->GetResponseInfo();
-    // If we get a certificate error, then there is a certificate in ssl_info,
-    // so GetResponseInfo() should never return NULL here.
-    DCHECK(response);
-    response_.ssl_info = response->ssl_info;
-  } else if (result == ERR_SSL_CLIENT_AUTH_CERT_NEEDED) {
-    const HttpResponseInfo* response = network_trans_->GetResponseInfo();
-    DCHECK(response);
-    response_.cert_request_info = response->cert_request_info;
-  } else if (response_.was_cached) {
-    DoneWritingToEntry(true);
-  }
-  return result;
-}
-
-// We received the response headers and there is no error.
-int HttpCache::Transaction::DoSuccessfulSendRequest() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoSuccessfulSendRequest"));
-
-  DCHECK(!new_response_);
-  const HttpResponseInfo* new_response = network_trans_->GetResponseInfo();
-  bool authentication_failure = false;
-
-  if (new_response->headers->response_code() == 401 ||
-      new_response->headers->response_code() == 407) {
-    auth_response_ = *new_response;
-    if (!reading_)
-      return OK;
-
-    // We initiated a second request the caller doesn't know about. We should be
-    // able to authenticate this request because we should have authenticated
-    // this URL moments ago.
-    if (IsReadyToRestartForAuth()) {
-      DCHECK(!response_.auth_challenge.get());
-      next_state_ = STATE_SEND_REQUEST_COMPLETE;
-      // In theory we should check to see if there are new cookies, but there
-      // is no way to do that from here.
-      return network_trans_->RestartWithAuth(AuthCredentials(), io_callback_);
-    }
-
-    // We have to perform cleanup at this point so that at least the next
-    // request can succeed.
-    authentication_failure = true;
-    if (entry_)
-      DoomPartialEntry(false);
-    mode_ = NONE;
-    partial_.reset();
-  }
-
-  new_response_ = new_response;
-  if (authentication_failure ||
-      (!ValidatePartialResponse() && !auth_response_.headers.get())) {
-    // Something went wrong with this request and we have to restart it.
-    // If we have an authentication response, we are exposed to weird things
-    // hapenning if the user cancels the authentication before we receive
-    // the new response.
-    net_log_.AddEvent(NetLog::TYPE_HTTP_CACHE_RE_SEND_PARTIAL_REQUEST);
-    UpdateTransactionPattern(PATTERN_NOT_COVERED);
-    response_ = HttpResponseInfo();
-    ResetNetworkTransaction();
-    new_response_ = NULL;
-    next_state_ = STATE_SEND_REQUEST;
-    return OK;
-  }
-
-  if (handling_206_ && mode_ == READ_WRITE && !truncated_ && !is_sparse_) {
-    // We have stored the full entry, but it changed and the server is
-    // sending a range. We have to delete the old entry.
-    UpdateTransactionPattern(PATTERN_NOT_COVERED);
-    DoneWritingToEntry(false);
-  }
-
-  if (mode_ == WRITE &&
-      transaction_pattern_ != PATTERN_ENTRY_CANT_CONDITIONALIZE) {
-    UpdateTransactionPattern(PATTERN_ENTRY_NOT_CACHED);
-  }
-
-  // Invalidate any cached GET with a successful PUT or DELETE.
-  if (mode_ == WRITE &&
-      (request_->method == "PUT" || request_->method == "DELETE")) {
-    if (NonErrorResponse(new_response->headers->response_code())) {
-      int ret = cache_->DoomEntry(cache_key_, NULL);
-      DCHECK_EQ(OK, ret);
-    }
-    cache_->DoneWritingToEntry(entry_, true);
-    entry_ = NULL;
-    mode_ = NONE;
-  }
-
-  // Invalidate any cached GET with a successful POST.
-  if (!(effective_load_flags_ & LOAD_DISABLE_CACHE) &&
-      request_->method == "POST" &&
-      NonErrorResponse(new_response->headers->response_code())) {
-    cache_->DoomMainEntryForUrl(request_->url);
-  }
-
-  RecordNoStoreHeaderHistogram(request_->load_flags, new_response);
-
-  if (new_response_->headers->response_code() == 416 &&
-      (request_->method == "GET" || request_->method == "POST")) {
-    // If there is an active entry it may be destroyed with this transaction.
-    response_ = *new_response_;
-    return OK;
-  }
-
-  // Are we expecting a response to a conditional query?
-  if (mode_ == READ_WRITE || mode_ == UPDATE) {
-    if (new_response->headers->response_code() == 304 || handling_206_) {
-      UpdateTransactionPattern(PATTERN_ENTRY_VALIDATED);
-      next_state_ = STATE_UPDATE_CACHED_RESPONSE;
-      return OK;
-    }
-    UpdateTransactionPattern(PATTERN_ENTRY_UPDATED);
-    mode_ = WRITE;
-  }
-
-  next_state_ = STATE_OVERWRITE_CACHED_RESPONSE;
-  return OK;
-}
-
-int HttpCache::Transaction::DoNetworkRead() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoNetworkRead"));
-
-  next_state_ = STATE_NETWORK_READ_COMPLETE;
-  return network_trans_->Read(read_buf_.get(), io_buf_len_, io_callback_);
-}
-
-int HttpCache::Transaction::DoNetworkReadComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoNetworkReadComplete"));
-
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  // If there is an error or we aren't saving the data, we are done; just wait
-  // until the destructor runs to see if we can keep the data.
-  if (mode_ == NONE || result < 0)
-    return result;
-
-  next_state_ = STATE_CACHE_WRITE_DATA;
-  return result;
-}
-
-int HttpCache::Transaction::DoInitEntry() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoInitEntry"));
-
-  DCHECK(!new_entry_);
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  if (mode_ == WRITE) {
-    next_state_ = STATE_DOOM_ENTRY;
-    return OK;
-  }
-
-  next_state_ = STATE_OPEN_ENTRY;
-  return OK;
-}
-
-int HttpCache::Transaction::DoOpenEntry() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoOpenEntry"));
-
-  DCHECK(!new_entry_);
-  next_state_ = STATE_OPEN_ENTRY_COMPLETE;
-  cache_pending_ = true;
-  net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_OPEN_ENTRY);
-  first_cache_access_since_ = TimeTicks::Now();
-  return cache_->OpenEntry(cache_key_, &new_entry_, this);
-}
-
-int HttpCache::Transaction::DoOpenEntryComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoOpenEntryComplete"));
-
-  // It is important that we go to STATE_ADD_TO_ENTRY whenever the result is
-  // OK, otherwise the cache will end up with an active entry without any
-  // transaction attached.
-  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_OPEN_ENTRY, result);
-  cache_pending_ = false;
-  if (result == OK) {
-    next_state_ = STATE_ADD_TO_ENTRY;
-    return OK;
-  }
-
-  if (result == ERR_CACHE_RACE) {
-    next_state_ = STATE_INIT_ENTRY;
-    return OK;
-  }
-
-  if (request_->method == "PUT" || request_->method == "DELETE" ||
-      (request_->method == "HEAD" && mode_ == READ_WRITE)) {
-    DCHECK(mode_ == READ_WRITE || mode_ == WRITE || request_->method == "HEAD");
-    mode_ = NONE;
-    next_state_ = STATE_SEND_REQUEST;
-    return OK;
-  }
-
-  if (mode_ == READ_WRITE) {
-    mode_ = WRITE;
-    next_state_ = STATE_CREATE_ENTRY;
-    return OK;
-  }
-  if (mode_ == UPDATE) {
-    // There is no cache entry to update; proceed without caching.
-    mode_ = NONE;
-    next_state_ = STATE_SEND_REQUEST;
-    return OK;
-  }
-  if (cache_->mode() == PLAYBACK)
-    DVLOG(1) << "Playback Cache Miss: " << request_->url;
-
-  // The entry does not exist, and we are not permitted to create a new entry,
-  // so we must fail.
-  return ERR_CACHE_MISS;
-}
-
-int HttpCache::Transaction::DoCreateEntry() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCreateEntry"));
-
-  DCHECK(!new_entry_);
-  next_state_ = STATE_CREATE_ENTRY_COMPLETE;
-  cache_pending_ = true;
-  net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_CREATE_ENTRY);
-  return cache_->CreateEntry(cache_key_, &new_entry_, this);
-}
-
-int HttpCache::Transaction::DoCreateEntryComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCreateEntryComplete"));
-
-  // It is important that we go to STATE_ADD_TO_ENTRY whenever the result is
-  // OK, otherwise the cache will end up with an active entry without any
-  // transaction attached.
-  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_CREATE_ENTRY,
-                                    result);
-  cache_pending_ = false;
-  next_state_ = STATE_ADD_TO_ENTRY;
-
-  if (result == ERR_CACHE_RACE) {
-    next_state_ = STATE_INIT_ENTRY;
-    return OK;
-  }
-
-  if (result != OK) {
-    // We have a race here: Maybe we failed to open the entry and decided to
-    // create one, but by the time we called create, another transaction already
-    // created the entry. If we want to eliminate this issue, we need an atomic
-    // OpenOrCreate() method exposed by the disk cache.
-    DLOG(WARNING) << "Unable to create cache entry";
-    mode_ = NONE;
-    if (partial_.get())
-      partial_->RestoreHeaders(&custom_request_->extra_headers);
-    next_state_ = STATE_SEND_REQUEST;
-  }
-  return OK;
-}
-
-int HttpCache::Transaction::DoDoomEntry() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoDoomEntry"));
-
-  next_state_ = STATE_DOOM_ENTRY_COMPLETE;
-  cache_pending_ = true;
-  if (first_cache_access_since_.is_null())
-    first_cache_access_since_ = TimeTicks::Now();
-  net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_DOOM_ENTRY);
-  return cache_->DoomEntry(cache_key_, this);
-}
-
-int HttpCache::Transaction::DoDoomEntryComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoDoomEntryComplete"));
-
-  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_DOOM_ENTRY, result);
-  next_state_ = STATE_CREATE_ENTRY;
-  cache_pending_ = false;
-  if (result == ERR_CACHE_RACE)
-    next_state_ = STATE_INIT_ENTRY;
-  return OK;
-}
-
-int HttpCache::Transaction::DoAddToEntry() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoAddToEntry"));
-
-  DCHECK(new_entry_);
-  cache_pending_ = true;
-  next_state_ = STATE_ADD_TO_ENTRY_COMPLETE;
-  net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_ADD_TO_ENTRY);
-  DCHECK(entry_lock_waiting_since_.is_null());
-  entry_lock_waiting_since_ = TimeTicks::Now();
-  int rv = cache_->AddTransactionToEntry(new_entry_, this);
-  if (rv == ERR_IO_PENDING) {
-    if (bypass_lock_for_test_) {
-      OnAddToEntryTimeout(entry_lock_waiting_since_);
-    } else {
-      int timeout_milliseconds = 20 * 1000;
-      if (partial_ && new_entry_->writer &&
-          new_entry_->writer->range_requested_) {
-        // Quickly timeout and bypass the cache if we're a range request and
-        // we're blocked by the reader/writer lock. Doing so eliminates a long
-        // running issue, http://crbug.com/31014, where two of the same media
-        // resources could not be played back simultaneously due to one locking
-        // the cache entry until the entire video was downloaded.
-        //
-        // Bypassing the cache is not ideal, as we are now ignoring the cache
-        // entirely for all range requests to a resource beyond the first. This
-        // is however a much more succinct solution than the alternatives, which
-        // would require somewhat significant changes to the http caching logic.
-        //
-        // Allow some timeout slack for the entry addition to complete in case
-        // the writer lock is imminently released; we want to avoid skipping
-        // the cache if at all possible. See http://crbug.com/408765
-        timeout_milliseconds = 25;
-      }
-      base::MessageLoop::current()->PostDelayedTask(
-          FROM_HERE,
-          base::Bind(&HttpCache::Transaction::OnAddToEntryTimeout,
-                     weak_factory_.GetWeakPtr(), entry_lock_waiting_since_),
-          TimeDelta::FromMilliseconds(timeout_milliseconds));
-    }
-  }
-  return rv;
-}
-
-int HttpCache::Transaction::DoAddToEntryComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoAddToEntryComplete"));
-
-  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_ADD_TO_ENTRY,
-                                    result);
-  const TimeDelta entry_lock_wait =
-      TimeTicks::Now() - entry_lock_waiting_since_;
-  UMA_HISTOGRAM_TIMES("HttpCache.EntryLockWait", entry_lock_wait);
-
-  entry_lock_waiting_since_ = TimeTicks();
-  DCHECK(new_entry_);
-  cache_pending_ = false;
-
-  if (result == OK)
-    entry_ = new_entry_;
-
-  // If there is a failure, the cache should have taken care of new_entry_.
-  new_entry_ = NULL;
-
-  if (result == ERR_CACHE_RACE) {
-    next_state_ = STATE_INIT_ENTRY;
-    return OK;
-  }
-
-  if (result == ERR_CACHE_LOCK_TIMEOUT) {
-    // The cache is busy, bypass it for this transaction.
-    mode_ = NONE;
-    next_state_ = STATE_SEND_REQUEST;
-    if (partial_) {
-      partial_->RestoreHeaders(&custom_request_->extra_headers);
-      partial_.reset();
-    }
-    return OK;
-  }
-
-  if (result != OK) {
-    NOTREACHED();
-    return result;
-  }
-
-  if (mode_ == WRITE) {
-    if (partial_.get())
-      partial_->RestoreHeaders(&custom_request_->extra_headers);
-    next_state_ = STATE_SEND_REQUEST;
-  } else {
-    // We have to read the headers from the cached entry.
-    DCHECK(mode_ & READ_META);
-    next_state_ = STATE_CACHE_READ_RESPONSE;
-  }
-  return OK;
-}
-
-// We may end up here multiple times for a given request.
-int HttpCache::Transaction::DoStartPartialCacheValidation() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoStartPartialCacheValidation"));
-
-  if (mode_ == NONE)
-    return OK;
-
-  next_state_ = STATE_COMPLETE_PARTIAL_CACHE_VALIDATION;
-  return partial_->ShouldValidateCache(entry_->disk_entry, io_callback_);
-}
-
-int HttpCache::Transaction::DoCompletePartialCacheValidation(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCompletePartialCacheValidation"));
-
-  if (!result) {
-    // This is the end of the request.
-    if (mode_ & WRITE) {
-      DoneWritingToEntry(true);
-    } else {
-      cache_->DoneReadingFromEntry(entry_, this);
-      entry_ = NULL;
-    }
-    return result;
-  }
-
-  if (result < 0)
-    return result;
-
-  partial_->PrepareCacheValidation(entry_->disk_entry,
-                                   &custom_request_->extra_headers);
-
-  if (reading_ && partial_->IsCurrentRangeCached()) {
-    next_state_ = STATE_CACHE_READ_DATA;
-    return OK;
-  }
-
-  return BeginCacheValidation();
-}
-
-// We received 304 or 206 and we want to update the cached response headers.
-int HttpCache::Transaction::DoUpdateCachedResponse() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoUpdateCachedResponse"));
-
-  next_state_ = STATE_UPDATE_CACHED_RESPONSE_COMPLETE;
-  int rv = OK;
-  // Update cached response based on headers in new_response.
-  // TODO(wtc): should we update cached certificate (response_.ssl_info), too?
-  response_.headers->Update(*new_response_->headers.get());
-  response_.response_time = new_response_->response_time;
-  response_.request_time = new_response_->request_time;
-  response_.network_accessed = new_response_->network_accessed;
-  response_.unused_since_prefetch = new_response_->unused_since_prefetch;
-
-  if (response_.headers->HasHeaderValue("cache-control", "no-store")) {
-    if (!entry_->doomed) {
-      int ret = cache_->DoomEntry(cache_key_, NULL);
-      DCHECK_EQ(OK, ret);
-    }
-  } else {
-    // If we are already reading, we already updated the headers for this
-    // request; doing it again will change Content-Length.
-    if (!reading_) {
-      target_state_ = STATE_UPDATE_CACHED_RESPONSE_COMPLETE;
-      next_state_ = STATE_CACHE_WRITE_RESPONSE;
-      rv = OK;
-    }
-  }
-  return rv;
-}
-
-int HttpCache::Transaction::DoUpdateCachedResponseComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoUpdateCachedResponseComplete"));
-
-  if (mode_ == UPDATE) {
-    DCHECK(!handling_206_);
-    // We got a "not modified" response and already updated the corresponding
-    // cache entry above.
-    //
-    // By closing the cached entry now, we make sure that the 304 rather than
-    // the cached 200 response, is what will be returned to the user.
-    DoneWritingToEntry(true);
-  } else if (entry_ && !handling_206_) {
-    DCHECK_EQ(READ_WRITE, mode_);
-    if (!partial_.get() || partial_->IsLastRange()) {
-      cache_->ConvertWriterToReader(entry_);
-      mode_ = READ;
-    }
-    // We no longer need the network transaction, so destroy it.
-    final_upload_progress_ = network_trans_->GetUploadProgress();
-    ResetNetworkTransaction();
-  } else if (entry_ && handling_206_ && truncated_ &&
-             partial_->initial_validation()) {
-    // We just finished the validation of a truncated entry, and the server
-    // is willing to resume the operation. Now we go back and start serving
-    // the first part to the user.
-    ResetNetworkTransaction();
-    new_response_ = NULL;
-    next_state_ = STATE_START_PARTIAL_CACHE_VALIDATION;
-    partial_->SetRangeToStartDownload();
-    return OK;
-  }
-  next_state_ = STATE_OVERWRITE_CACHED_RESPONSE;
-  return OK;
-}
-
-int HttpCache::Transaction::DoOverwriteCachedResponse() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoOverwriteCachedResponse"));
-
-  if (mode_ & READ) {
-    next_state_ = STATE_PARTIAL_HEADERS_RECEIVED;
-    return OK;
-  }
-
-  // We change the value of Content-Length for partial content.
-  if (handling_206_ && partial_.get())
-    partial_->FixContentLength(new_response_->headers.get());
-
-  response_ = *new_response_;
-
-  if (request_->method == "HEAD") {
-    // This response is replacing the cached one.
-    DoneWritingToEntry(false);
-    mode_ = NONE;
-    new_response_ = NULL;
-    return OK;
-  }
-
-  if (handling_206_ && !CanResume(false)) {
-    // There is no point in storing this resource because it will never be used.
-    // This may change if we support LOAD_ONLY_FROM_CACHE with sparse entries.
-    DoneWritingToEntry(false);
-    if (partial_.get())
-      partial_->FixResponseHeaders(response_.headers.get(), true);
-    next_state_ = STATE_PARTIAL_HEADERS_RECEIVED;
-    return OK;
-  }
-
-  target_state_ = STATE_TRUNCATE_CACHED_DATA;
-  next_state_ = truncated_ ? STATE_CACHE_WRITE_TRUNCATED_RESPONSE :
-                             STATE_CACHE_WRITE_RESPONSE;
-  return OK;
-}
-
-int HttpCache::Transaction::DoTruncateCachedData() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoTruncateCachedData"));
-
-  next_state_ = STATE_TRUNCATE_CACHED_DATA_COMPLETE;
-  if (!entry_)
-    return OK;
-  if (net_log_.IsLogging())
-    net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_WRITE_DATA);
-  // Truncate the stream.
-  return WriteToEntry(kResponseContentIndex, 0, NULL, 0, io_callback_);
-}
-
-int HttpCache::Transaction::DoTruncateCachedDataComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoTruncateCachedDataComplete"));
-
-  if (entry_) {
-    if (net_log_.IsLogging()) {
-      net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_WRITE_DATA,
-                                        result);
-    }
-  }
-
-  next_state_ = STATE_TRUNCATE_CACHED_METADATA;
-  return OK;
-}
-
-int HttpCache::Transaction::DoTruncateCachedMetadata() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoTruncateCachedMetadata"));
-
-  next_state_ = STATE_TRUNCATE_CACHED_METADATA_COMPLETE;
-  if (!entry_)
-    return OK;
-
-  if (net_log_.IsLogging())
-    net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_WRITE_INFO);
-  return WriteToEntry(kMetadataIndex, 0, NULL, 0, io_callback_);
-}
-
-int HttpCache::Transaction::DoTruncateCachedMetadataComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoTruncateCachedMetadataComplete"));
-
-  if (entry_) {
-    if (net_log_.IsLogging()) {
-      net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_WRITE_INFO,
-                                        result);
-    }
-  }
-
-  next_state_ = STATE_PARTIAL_HEADERS_RECEIVED;
-  return OK;
-}
-
-int HttpCache::Transaction::DoPartialHeadersReceived() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoPartialHeadersReceived"));
-
-  new_response_ = NULL;
-  if (entry_ && !partial_.get() &&
-      entry_->disk_entry->GetDataSize(kMetadataIndex))
-    next_state_ = STATE_CACHE_READ_METADATA;
-
-  if (!partial_.get())
-    return OK;
-
-  if (reading_) {
-    if (network_trans_.get()) {
-      next_state_ = STATE_NETWORK_READ;
-    } else {
-      next_state_ = STATE_CACHE_READ_DATA;
-    }
-  } else if (mode_ != NONE) {
-    // We are about to return the headers for a byte-range request to the user,
-    // so let's fix them.
-    partial_->FixResponseHeaders(response_.headers.get(), true);
-  }
-  return OK;
-}
-
-int HttpCache::Transaction::DoCacheReadResponse() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheReadResponse"));
-
-  DCHECK(entry_);
-  next_state_ = STATE_CACHE_READ_RESPONSE_COMPLETE;
-
-  io_buf_len_ = entry_->disk_entry->GetDataSize(kResponseInfoIndex);
-  read_buf_ = new IOBuffer(io_buf_len_);
-
-  net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_READ_INFO);
-  return entry_->disk_entry->ReadData(kResponseInfoIndex, 0, read_buf_.get(),
-                                      io_buf_len_, io_callback_);
-}
-
-int HttpCache::Transaction::DoCacheReadResponseComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheReadResponseComplete"));
-
-  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_READ_INFO, result);
-  if (result != io_buf_len_ ||
-      !HttpCache::ParseResponseInfo(read_buf_->data(), io_buf_len_,
-                                    &response_, &truncated_)) {
-    return OnCacheReadError(result, true);
-  }
-
-  // cert_cache() will be null if the CertCacheTrial field trial is disabled.
-  if (cache_->cert_cache() && response_.ssl_info.is_valid())
-    ReadCertChain();
-
-  // Some resources may have slipped in as truncated when they're not.
-  int current_size = entry_->disk_entry->GetDataSize(kResponseContentIndex);
-  if (response_.headers->GetContentLength() == current_size)
-    truncated_ = false;
-
-  if ((response_.unused_since_prefetch &&
-       !(request_->load_flags & LOAD_PREFETCH)) ||
-      (!response_.unused_since_prefetch &&
-       (request_->load_flags & LOAD_PREFETCH))) {
-    // Either this is the first use of an entry since it was prefetched or
-    // this is a prefetch. The value of response.unused_since_prefetch is valid
-    // for this transaction but the bit needs to be flipped in storage.
-    next_state_ = STATE_TOGGLE_UNUSED_SINCE_PREFETCH;
-    return OK;
-  }
-
-  next_state_ = STATE_CACHE_DISPATCH_VALIDATION;
-  return OK;
-}
-
-int HttpCache::Transaction::DoCacheDispatchValidation() {
-  // We now have access to the cache entry.
-  //
-  //  o if we are a reader for the transaction, then we can start reading the
-  //    cache entry.
-  //
-  //  o if we can read or write, then we should check if the cache entry needs
-  //    to be validated and then issue a network request if needed or just read
-  //    from the cache if the cache entry is already valid.
-  //
-  //  o if we are set to UPDATE, then we are handling an externally
-  //    conditionalized request (if-modified-since / if-none-match). We check
-  //    if the request headers define a validation request.
-  //
-  int result = ERR_FAILED;
-  switch (mode_) {
-    case READ:
-      UpdateTransactionPattern(PATTERN_ENTRY_USED);
-      result = BeginCacheRead();
-      break;
-    case READ_WRITE:
-      result = BeginPartialCacheValidation();
-      break;
-    case UPDATE:
-      result = BeginExternallyConditionalizedRequest();
-      break;
-    case WRITE:
-    default:
-      NOTREACHED();
-  }
-  return result;
-}
-
-int HttpCache::Transaction::DoCacheToggleUnusedSincePrefetch() {
-  // Write back the toggled value for the next use of this entry.
-  response_.unused_since_prefetch = !response_.unused_since_prefetch;
-
-  // TODO(jkarlin): If DoUpdateCachedResponse is also called for this
-  // transaction then metadata will be written to cache twice. If prefetching
-  // becomes more common, consider combining the writes.
-  target_state_ = STATE_TOGGLE_UNUSED_SINCE_PREFETCH_COMPLETE;
-  next_state_ = STATE_CACHE_WRITE_RESPONSE;
-  return OK;
-}
-
-int HttpCache::Transaction::DoCacheToggleUnusedSincePrefetchComplete(
-    int result) {
-  // Restore the original value for this transaction.
-  response_.unused_since_prefetch = !response_.unused_since_prefetch;
-  next_state_ = STATE_CACHE_DISPATCH_VALIDATION;
-  return OK;
-}
-
-int HttpCache::Transaction::DoCacheWriteResponse() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheWriteResponse"));
-
-  if (entry_) {
-    if (net_log_.IsLogging())
-      net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_WRITE_INFO);
-  }
-  return WriteResponseInfoToEntry(false);
-}
-
-int HttpCache::Transaction::DoCacheWriteTruncatedResponse() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheWriteTruncatedResponse"));
-
-  if (entry_) {
-    if (net_log_.IsLogging())
-      net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_WRITE_INFO);
-  }
-  return WriteResponseInfoToEntry(true);
-}
-
-int HttpCache::Transaction::DoCacheWriteResponseComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheWriteResponseComplete"));
-
-  next_state_ = target_state_;
-  target_state_ = STATE_NONE;
-  if (!entry_)
-    return OK;
-  if (net_log_.IsLogging()) {
-    net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_WRITE_INFO,
-                                      result);
-  }
-
-  // Balance the AddRef from WriteResponseInfoToEntry.
-  if (result != io_buf_len_) {
-    DLOG(ERROR) << "failed to write response info to cache";
-    DoneWritingToEntry(false);
-  }
-  return OK;
-}
-
-int HttpCache::Transaction::DoCacheReadMetadata() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheReadMetadata"));
-
-  DCHECK(entry_);
-  DCHECK(!response_.metadata.get());
-  next_state_ = STATE_CACHE_READ_METADATA_COMPLETE;
-
-  response_.metadata =
-      new IOBufferWithSize(entry_->disk_entry->GetDataSize(kMetadataIndex));
-
-  net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_READ_INFO);
-  return entry_->disk_entry->ReadData(kMetadataIndex, 0,
-                                      response_.metadata.get(),
-                                      response_.metadata->size(),
-                                      io_callback_);
-}
-
-int HttpCache::Transaction::DoCacheReadMetadataComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheReadMetadataComplete"));
-
-  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_READ_INFO, result);
-  if (result != response_.metadata->size())
-    return OnCacheReadError(result, false);
-  return OK;
-}
-
-int HttpCache::Transaction::DoCacheQueryData() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheQueryData"));
-
-  next_state_ = STATE_CACHE_QUERY_DATA_COMPLETE;
-  return entry_->disk_entry->ReadyForSparseIO(io_callback_);
-}
-
-int HttpCache::Transaction::DoCacheQueryDataComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheQueryDataComplete"));
-
-  DCHECK_EQ(OK, result);
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  return ValidateEntryHeadersAndContinue();
-}
-
-int HttpCache::Transaction::DoCacheReadData() {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheReadData"));
-
-  DCHECK(entry_);
-  next_state_ = STATE_CACHE_READ_DATA_COMPLETE;
-
-  if (net_log_.IsLogging())
-    net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_READ_DATA);
-  if (partial_.get()) {
-    return partial_->CacheRead(entry_->disk_entry, read_buf_.get(), io_buf_len_,
-                               io_callback_);
-  }
-
-  return entry_->disk_entry->ReadData(kResponseContentIndex, read_offset_,
-                                      read_buf_.get(), io_buf_len_,
-                                      io_callback_);
-}
-
-int HttpCache::Transaction::DoCacheReadDataComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheReadDataComplete"));
-
-  if (net_log_.IsLogging()) {
-    net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_READ_DATA,
-                                      result);
-  }
-
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  if (partial_.get()) {
-    // Partial requests are confusing to report in histograms because they may
-    // have multiple underlying requests.
-    UpdateTransactionPattern(PATTERN_NOT_COVERED);
-    return DoPartialCacheReadCompleted(result);
-  }
-
-  if (result > 0) {
-    read_offset_ += result;
-  } else if (result == 0) {  // End of file.
-    RecordHistograms();
-    cache_->DoneReadingFromEntry(entry_, this);
-    entry_ = NULL;
-  } else {
-    return OnCacheReadError(result, false);
-  }
-  return result;
-}
-
-int HttpCache::Transaction::DoCacheWriteData(int num_bytes) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheWriteData"));
-
-  next_state_ = STATE_CACHE_WRITE_DATA_COMPLETE;
-  write_len_ = num_bytes;
-  if (entry_) {
-    if (net_log_.IsLogging())
-      net_log_.BeginEvent(NetLog::TYPE_HTTP_CACHE_WRITE_DATA);
-  }
-
-  return AppendResponseDataToEntry(read_buf_.get(), num_bytes, io_callback_);
-}
-
-int HttpCache::Transaction::DoCacheWriteDataComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION(
-          "422516 HttpCache::Transaction::DoCacheWriteDataComplete"));
-
-  if (entry_) {
-    if (net_log_.IsLogging()) {
-      net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HTTP_CACHE_WRITE_DATA,
-                                        result);
-    }
-  }
-  // Balance the AddRef from DoCacheWriteData.
-  if (!cache_.get())
-    return ERR_UNEXPECTED;
-
-  if (result != write_len_) {
-    DLOG(ERROR) << "failed to write response data to cache";
-    DoneWritingToEntry(false);
-
-    // We want to ignore errors writing to disk and just keep reading from
-    // the network.
-    result = write_len_;
-  } else if (!done_reading_ && entry_) {
-    int current_size = entry_->disk_entry->GetDataSize(kResponseContentIndex);
-    int64 body_size = response_.headers->GetContentLength();
-    if (body_size >= 0 && body_size <= current_size)
-      done_reading_ = true;
-  }
-
-  if (partial_.get()) {
-    // This may be the last request.
-    if (!(result == 0 && !truncated_ &&
-          (partial_->IsLastRange() || mode_ == WRITE)))
-      return DoPartialNetworkReadCompleted(result);
-  }
-
-  if (result == 0) {
-    // End of file. This may be the result of a connection problem so see if we
-    // have to keep the entry around to be flagged as truncated later on.
-    if (done_reading_ || !entry_ || partial_.get() ||
-        response_.headers->GetContentLength() <= 0)
-      DoneWritingToEntry(true);
-  }
-
-  return result;
-}
-
-//-----------------------------------------------------------------------------
-
-void HttpCache::Transaction::ReadCertChain() {
-  std::string key =
-      GetCacheKeyForCert(response_.ssl_info.cert->os_cert_handle());
-  const X509Certificate::OSCertHandles& intermediates =
-      response_.ssl_info.cert->GetIntermediateCertificates();
-  int dist_from_root = intermediates.size();
-
-  scoped_refptr<SharedChainData> shared_chain_data(
-      new SharedChainData(intermediates.size() + 1, TimeTicks::Now()));
-  cache_->cert_cache()->GetCertificate(key,
-                                       base::Bind(&OnCertReadIOComplete,
-                                                  dist_from_root,
-                                                  true /* is leaf */,
-                                                  shared_chain_data));
-
-  for (X509Certificate::OSCertHandles::const_iterator it =
-           intermediates.begin();
-       it != intermediates.end();
-       ++it) {
-    --dist_from_root;
-    key = GetCacheKeyForCert(*it);
-    cache_->cert_cache()->GetCertificate(key,
-                                         base::Bind(&OnCertReadIOComplete,
-                                                    dist_from_root,
-                                                    false /* is not leaf */,
-                                                    shared_chain_data));
-  }
-  DCHECK_EQ(0, dist_from_root);
-}
-
-void HttpCache::Transaction::WriteCertChain() {
-  const X509Certificate::OSCertHandles& intermediates =
-      response_.ssl_info.cert->GetIntermediateCertificates();
-  int dist_from_root = intermediates.size();
-
-  scoped_refptr<SharedChainData> shared_chain_data(
-      new SharedChainData(intermediates.size() + 1, TimeTicks::Now()));
-  cache_->cert_cache()->SetCertificate(
-      response_.ssl_info.cert->os_cert_handle(),
-      base::Bind(&OnCertWriteIOComplete,
-                 dist_from_root,
-                 true /* is leaf */,
-                 shared_chain_data));
-  for (X509Certificate::OSCertHandles::const_iterator it =
-           intermediates.begin();
-       it != intermediates.end();
-       ++it) {
-    --dist_from_root;
-    cache_->cert_cache()->SetCertificate(*it,
-                                         base::Bind(&OnCertWriteIOComplete,
-                                                    dist_from_root,
-                                                    false /* is not leaf */,
-                                                    shared_chain_data));
-  }
-  DCHECK_EQ(0, dist_from_root);
-}
-
-void HttpCache::Transaction::SetRequest(const BoundNetLog& net_log,
-                                        const HttpRequestInfo* request) {
-  net_log_ = net_log;
-  request_ = request;
-  effective_load_flags_ = request_->load_flags;
-
-  switch (cache_->mode()) {
-    case NORMAL:
-      break;
-    case RECORD:
-      // When in record mode, we want to NEVER load from the cache.
-      // The reason for this is because we save the Set-Cookie headers
-      // (intentionally).  If we read from the cache, we replay them
-      // prematurely.
-      effective_load_flags_ |= LOAD_BYPASS_CACHE;
-      break;
-    case PLAYBACK:
-      // When in playback mode, we want to load exclusively from the cache.
-      effective_load_flags_ |= LOAD_ONLY_FROM_CACHE;
-      break;
-    case DISABLE:
-      effective_load_flags_ |= LOAD_DISABLE_CACHE;
-      break;
-  }
-
-  // Some headers imply load flags.  The order here is significant.
-  //
-  //   LOAD_DISABLE_CACHE   : no cache read or write
-  //   LOAD_BYPASS_CACHE    : no cache read
-  //   LOAD_VALIDATE_CACHE  : no cache read unless validation
-  //
-  // The former modes trump latter modes, so if we find a matching header we
-  // can stop iterating kSpecialHeaders.
-  //
-  static const struct {
-    const HeaderNameAndValue* search;
-    int load_flag;
-  } kSpecialHeaders[] = {
-    { kPassThroughHeaders, LOAD_DISABLE_CACHE },
-    { kForceFetchHeaders, LOAD_BYPASS_CACHE },
-    { kForceValidateHeaders, LOAD_VALIDATE_CACHE },
-  };
-
-  bool range_found = false;
-  bool external_validation_error = false;
-  bool special_headers = false;
-
-  if (request_->extra_headers.HasHeader(HttpRequestHeaders::kRange))
-    range_found = true;
-
-  for (size_t i = 0; i < arraysize(kSpecialHeaders); ++i) {
-    if (HeaderMatches(request_->extra_headers, kSpecialHeaders[i].search)) {
-      effective_load_flags_ |= kSpecialHeaders[i].load_flag;
-      special_headers = true;
-      break;
-    }
-  }
-
-  // Check for conditionalization headers which may correspond with a
-  // cache validation request.
-  for (size_t i = 0; i < arraysize(kValidationHeaders); ++i) {
-    const ValidationHeaderInfo& info = kValidationHeaders[i];
-    std::string validation_value;
-    if (request_->extra_headers.GetHeader(
-            info.request_header_name, &validation_value)) {
-      if (!external_validation_.values[i].empty() ||
-          validation_value.empty()) {
-        external_validation_error = true;
-      }
-      external_validation_.values[i] = validation_value;
-      external_validation_.initialized = true;
-    }
-  }
-
-  if (range_found || special_headers || external_validation_.initialized) {
-    // Log the headers before request_ is modified.
-    std::string empty;
-    net_log_.AddEvent(
-        NetLog::TYPE_HTTP_CACHE_CALLER_REQUEST_HEADERS,
-        base::Bind(&HttpRequestHeaders::NetLogCallback,
-                   base::Unretained(&request_->extra_headers), &empty));
-  }
-
-  // We don't support ranges and validation headers.
-  if (range_found && external_validation_.initialized) {
-    LOG(WARNING) << "Byte ranges AND validation headers found.";
-    effective_load_flags_ |= LOAD_DISABLE_CACHE;
-  }
-
-  // If there is more than one validation header, we can't treat this request as
-  // a cache validation, since we don't know for sure which header the server
-  // will give us a response for (and they could be contradictory).
-  if (external_validation_error) {
-    LOG(WARNING) << "Multiple or malformed validation headers found.";
-    effective_load_flags_ |= LOAD_DISABLE_CACHE;
-  }
-
-  if (range_found && !(effective_load_flags_ & LOAD_DISABLE_CACHE)) {
-    UpdateTransactionPattern(PATTERN_NOT_COVERED);
-    partial_.reset(new PartialData);
-    if (request_->method == "GET" && partial_->Init(request_->extra_headers)) {
-      // We will be modifying the actual range requested to the server, so
-      // let's remove the header here.
-      custom_request_.reset(new HttpRequestInfo(*request_));
-      custom_request_->extra_headers.RemoveHeader(HttpRequestHeaders::kRange);
-      request_ = custom_request_.get();
-      partial_->SetHeaders(custom_request_->extra_headers);
-    } else {
-      // The range is invalid or we cannot handle it properly.
-      VLOG(1) << "Invalid byte range found.";
-      effective_load_flags_ |= LOAD_DISABLE_CACHE;
-      partial_.reset(NULL);
-    }
-  }
-}
-
-bool HttpCache::Transaction::ShouldPassThrough() {
-  // We may have a null disk_cache if there is an error we cannot recover from,
-  // like not enough disk space, or sharing violations.
-  if (!cache_->disk_cache_.get())
-    return true;
-
-  // When using the record/playback modes, we always use the cache
-  // and we never pass through.
-  if (cache_->mode() == RECORD || cache_->mode() == PLAYBACK)
-    return false;
-
-  if (effective_load_flags_ & LOAD_DISABLE_CACHE)
-    return true;
-
-  if (request_->method == "GET" || request_->method == "HEAD")
-    return false;
-
-  if (request_->method == "POST" && request_->upload_data_stream &&
-      request_->upload_data_stream->identifier()) {
-    return false;
-  }
-
-  if (request_->method == "PUT" && request_->upload_data_stream)
-    return false;
-
-  if (request_->method == "DELETE")
-    return false;
-
-  return true;
-}
-
-int HttpCache::Transaction::BeginCacheRead() {
-  // We don't support any combination of LOAD_ONLY_FROM_CACHE and byte ranges.
-  if (response_.headers->response_code() == 206 || partial_.get()) {
-    NOTREACHED();
-    return ERR_CACHE_MISS;
-  }
-
-  if (request_->method == "HEAD")
-    FixHeadersForHead();
-
-  // We don't have the whole resource.
-  if (truncated_)
-    return ERR_CACHE_MISS;
-
-  if (entry_->disk_entry->GetDataSize(kMetadataIndex))
-    next_state_ = STATE_CACHE_READ_METADATA;
-
-  return OK;
-}
-
-int HttpCache::Transaction::BeginCacheValidation() {
-  DCHECK(mode_ == READ_WRITE);
-
-  ValidationType required_validation = RequiresValidation();
-
-  bool skip_validation = (required_validation == VALIDATION_NONE);
-
-  if (required_validation == VALIDATION_ASYNCHRONOUS &&
-      !(request_->method == "GET" && (truncated_ || partial_)) && cache_ &&
-      cache_->use_stale_while_revalidate()) {
-    TriggerAsyncValidation();
-    skip_validation = true;
-  }
-
-  if (request_->method == "HEAD" &&
-      (truncated_ || response_.headers->response_code() == 206)) {
-    DCHECK(!partial_);
-    if (skip_validation)
-      return SetupEntryForRead();
-
-    // Bail out!
-    next_state_ = STATE_SEND_REQUEST;
-    mode_ = NONE;
-    return OK;
-  }
-
-  if (truncated_) {
-    // Truncated entries can cause partial gets, so we shouldn't record this
-    // load in histograms.
-    UpdateTransactionPattern(PATTERN_NOT_COVERED);
-    skip_validation = !partial_->initial_validation();
-  }
-
-  if (partial_.get() && (is_sparse_ || truncated_) &&
-      (!partial_->IsCurrentRangeCached() || invalid_range_)) {
-    // Force revalidation for sparse or truncated entries. Note that we don't
-    // want to ignore the regular validation logic just because a byte range was
-    // part of the request.
-    skip_validation = false;
-  }
-
-  if (skip_validation) {
-    // TODO(ricea): Is this pattern okay for asynchronous revalidations?
-    UpdateTransactionPattern(PATTERN_ENTRY_USED);
-    RecordOfflineStatus(effective_load_flags_, OFFLINE_STATUS_FRESH_CACHE);
-    return SetupEntryForRead();
-  } else {
-    // Make the network request conditional, to see if we may reuse our cached
-    // response.  If we cannot do so, then we just resort to a normal fetch.
-    // Our mode remains READ_WRITE for a conditional request.  Even if the
-    // conditionalization fails, we don't switch to WRITE mode until we
-    // know we won't be falling back to using the cache entry in the
-    // LOAD_FROM_CACHE_IF_OFFLINE case.
-    if (!ConditionalizeRequest()) {
-      couldnt_conditionalize_request_ = true;
-      UpdateTransactionPattern(PATTERN_ENTRY_CANT_CONDITIONALIZE);
-      if (partial_.get())
-        return DoRestartPartialRequest();
-
-      DCHECK_NE(206, response_.headers->response_code());
-    }
-    next_state_ = STATE_SEND_REQUEST;
-  }
-  return OK;
-}
-
-int HttpCache::Transaction::BeginPartialCacheValidation() {
-  DCHECK(mode_ == READ_WRITE);
-
-  if (response_.headers->response_code() != 206 && !partial_.get() &&
-      !truncated_) {
-    return BeginCacheValidation();
-  }
-
-  // Partial requests should not be recorded in histograms.
-  UpdateTransactionPattern(PATTERN_NOT_COVERED);
-  if (range_requested_) {
-    next_state_ = STATE_CACHE_QUERY_DATA;
-    return OK;
-  }
-
-  // The request is not for a range, but we have stored just ranges.
-
-  if (request_->method == "HEAD")
-    return BeginCacheValidation();
-
-  partial_.reset(new PartialData());
-  partial_->SetHeaders(request_->extra_headers);
-  if (!custom_request_.get()) {
-    custom_request_.reset(new HttpRequestInfo(*request_));
-    request_ = custom_request_.get();
-  }
-
-  return ValidateEntryHeadersAndContinue();
-}
-
-// This should only be called once per request.
-int HttpCache::Transaction::ValidateEntryHeadersAndContinue() {
-  DCHECK(mode_ == READ_WRITE);
-
-  if (!partial_->UpdateFromStoredHeaders(
-          response_.headers.get(), entry_->disk_entry, truncated_)) {
-    return DoRestartPartialRequest();
-  }
-
-  if (response_.headers->response_code() == 206)
-    is_sparse_ = true;
-
-  if (!partial_->IsRequestedRangeOK()) {
-    // The stored data is fine, but the request may be invalid.
-    invalid_range_ = true;
-  }
-
-  next_state_ = STATE_START_PARTIAL_CACHE_VALIDATION;
-  return OK;
-}
-
-int HttpCache::Transaction::BeginExternallyConditionalizedRequest() {
-  DCHECK_EQ(UPDATE, mode_);
-  DCHECK(external_validation_.initialized);
-
-  for (size_t i = 0;  i < arraysize(kValidationHeaders); i++) {
-    if (external_validation_.values[i].empty())
-      continue;
-    // Retrieve either the cached response's "etag" or "last-modified" header.
-    std::string validator;
-    response_.headers->EnumerateHeader(
-        NULL,
-        kValidationHeaders[i].related_response_header_name,
-        &validator);
-
-    if (response_.headers->response_code() != 200 || truncated_ ||
-        validator.empty() || validator != external_validation_.values[i]) {
-      // The externally conditionalized request is not a validation request
-      // for our existing cache entry. Proceed with caching disabled.
-      UpdateTransactionPattern(PATTERN_NOT_COVERED);
-      DoneWritingToEntry(true);
-    }
-  }
-
-  // TODO(ricea): This calculation is expensive to perform just to collect
-  // statistics. Either remove it or use the result, depending on the result of
-  // the experiment.
-  ExternallyConditionalizedType type =
-      EXTERNALLY_CONDITIONALIZED_CACHE_USABLE;
-  if (mode_ == NONE)
-    type = EXTERNALLY_CONDITIONALIZED_MISMATCHED_VALIDATORS;
-  else if (RequiresValidation())
-    type = EXTERNALLY_CONDITIONALIZED_CACHE_REQUIRES_VALIDATION;
-
-  // TODO(ricea): Add CACHE_USABLE_STALE once stale-while-revalidate CL landed.
-  // TODO(ricea): Either remove this histogram or make it permanent by M40.
-  UMA_HISTOGRAM_ENUMERATION("HttpCache.ExternallyConditionalized",
-                            type,
-                            EXTERNALLY_CONDITIONALIZED_MAX);
-
-  next_state_ = STATE_SEND_REQUEST;
-  return OK;
-}
-
-int HttpCache::Transaction::RestartNetworkRequest() {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(network_trans_.get());
-  DCHECK_EQ(STATE_NONE, next_state_);
-
-  next_state_ = STATE_SEND_REQUEST_COMPLETE;
-  int rv = network_trans_->RestartIgnoringLastError(io_callback_);
-  if (rv != ERR_IO_PENDING)
-    return DoLoop(rv);
-  return rv;
-}
-
-int HttpCache::Transaction::RestartNetworkRequestWithCertificate(
-    X509Certificate* client_cert) {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(network_trans_.get());
-  DCHECK_EQ(STATE_NONE, next_state_);
-
-  next_state_ = STATE_SEND_REQUEST_COMPLETE;
-  int rv = network_trans_->RestartWithCertificate(client_cert, io_callback_);
-  if (rv != ERR_IO_PENDING)
-    return DoLoop(rv);
-  return rv;
-}
-
-int HttpCache::Transaction::RestartNetworkRequestWithAuth(
-    const AuthCredentials& credentials) {
-  DCHECK(mode_ & WRITE || mode_ == NONE);
-  DCHECK(network_trans_.get());
-  DCHECK_EQ(STATE_NONE, next_state_);
-
-  next_state_ = STATE_SEND_REQUEST_COMPLETE;
-  int rv = network_trans_->RestartWithAuth(credentials, io_callback_);
-  if (rv != ERR_IO_PENDING)
-    return DoLoop(rv);
-  return rv;
-}
-
-ValidationType HttpCache::Transaction::RequiresValidation() {
-  // TODO(darin): need to do more work here:
-  //  - make sure we have a matching request method
-  //  - watch out for cached responses that depend on authentication
-
-  // In playback mode, nothing requires validation.
-  if (cache_->mode() == net::HttpCache::PLAYBACK)
-    return VALIDATION_NONE;
-
-  if (response_.vary_data.is_valid() &&
-      !response_.vary_data.MatchesRequest(*request_,
-                                          *response_.headers.get())) {
-    vary_mismatch_ = true;
-    return VALIDATION_SYNCHRONOUS;
-  }
-
-  if (effective_load_flags_ & LOAD_PREFERRING_CACHE)
-    return VALIDATION_NONE;
-
-  if (response_.unused_since_prefetch &&
-      !(effective_load_flags_ & LOAD_PREFETCH) &&
-      response_.headers->GetCurrentAge(
-          response_.request_time, response_.response_time,
-          cache_->clock_->Now()) < TimeDelta::FromMinutes(kPrefetchReuseMins)) {
-    // The first use of a resource after prefetch within a short window skips
-    // validation.
-    return VALIDATION_NONE;
-  }
-
-  if (effective_load_flags_ & (LOAD_VALIDATE_CACHE | LOAD_ASYNC_REVALIDATION))
-    return VALIDATION_SYNCHRONOUS;
-
-  if (request_->method == "PUT" || request_->method == "DELETE")
-    return VALIDATION_SYNCHRONOUS;
-
-  ValidationType validation_required_by_headers =
-      response_.headers->RequiresValidation(response_.request_time,
-                                            response_.response_time,
-                                            cache_->clock_->Now());
-
-  if (validation_required_by_headers == VALIDATION_ASYNCHRONOUS) {
-    // Asynchronous revalidation is only supported for GET and HEAD methods.
-    if (request_->method != "GET" && request_->method != "HEAD")
-      return VALIDATION_SYNCHRONOUS;
-  }
-
-  return validation_required_by_headers;
-}
-
-bool HttpCache::Transaction::ConditionalizeRequest() {
-  DCHECK(response_.headers.get());
-
-  if (request_->method == "PUT" || request_->method == "DELETE")
-    return false;
-
-  // This only makes sense for cached 200 or 206 responses.
-  if (response_.headers->response_code() != 200 &&
-      response_.headers->response_code() != 206) {
-    return false;
-  }
-
-  if (fail_conditionalization_for_test_)
-    return false;
-
-  DCHECK(response_.headers->response_code() != 206 ||
-         response_.headers->HasStrongValidators());
-
-  // Just use the first available ETag and/or Last-Modified header value.
-  // TODO(darin): Or should we use the last?
-
-  std::string etag_value;
-  if (response_.headers->GetHttpVersion() >= HttpVersion(1, 1))
-    response_.headers->EnumerateHeader(NULL, "etag", &etag_value);
-
-  std::string last_modified_value;
-  if (!vary_mismatch_) {
-    response_.headers->EnumerateHeader(NULL, "last-modified",
-                                       &last_modified_value);
-  }
-
-  if (etag_value.empty() && last_modified_value.empty())
-    return false;
-
-  if (!partial_.get()) {
-    // Need to customize the request, so this forces us to allocate :(
-    custom_request_.reset(new HttpRequestInfo(*request_));
-    request_ = custom_request_.get();
-  }
-  DCHECK(custom_request_.get());
-
-  bool use_if_range = partial_.get() && !partial_->IsCurrentRangeCached() &&
-                      !invalid_range_;
-
-  if (!use_if_range) {
-    // stale-while-revalidate is not useful when we only have a partial response
-    // cached, so don't set the header in that case.
-    HttpResponseHeaders::FreshnessLifetimes lifetimes =
-        response_.headers->GetFreshnessLifetimes(response_.response_time);
-    if (lifetimes.staleness > TimeDelta()) {
-      TimeDelta current_age = response_.headers->GetCurrentAge(
-          response_.request_time, response_.response_time,
-          cache_->clock_->Now());
-
-      custom_request_->extra_headers.SetHeader(
-          kFreshnessHeader,
-          base::StringPrintf("max-age=%" PRId64
-                             ",stale-while-revalidate=%" PRId64 ",age=%" PRId64,
-                             lifetimes.freshness.InSeconds(),
-                             lifetimes.staleness.InSeconds(),
-                             current_age.InSeconds()));
-    }
-  }
-
-  if (!etag_value.empty()) {
-    if (use_if_range) {
-      // We don't want to switch to WRITE mode if we don't have this block of a
-      // byte-range request because we may have other parts cached.
-      custom_request_->extra_headers.SetHeader(
-          HttpRequestHeaders::kIfRange, etag_value);
-    } else {
-      custom_request_->extra_headers.SetHeader(
-          HttpRequestHeaders::kIfNoneMatch, etag_value);
-    }
-    // For byte-range requests, make sure that we use only one way to validate
-    // the request.
-    if (partial_.get() && !partial_->IsCurrentRangeCached())
-      return true;
-  }
-
-  if (!last_modified_value.empty()) {
-    if (use_if_range) {
-      custom_request_->extra_headers.SetHeader(
-          HttpRequestHeaders::kIfRange, last_modified_value);
-    } else {
-      custom_request_->extra_headers.SetHeader(
-          HttpRequestHeaders::kIfModifiedSince, last_modified_value);
-    }
-  }
-
-  return true;
-}
-
-// We just received some headers from the server. We may have asked for a range,
-// in which case partial_ has an object. This could be the first network request
-// we make to fulfill the original request, or we may be already reading (from
-// the net and / or the cache). If we are not expecting a certain response, we
-// just bypass the cache for this request (but again, maybe we are reading), and
-// delete partial_ (so we are not able to "fix" the headers that we return to
-// the user). This results in either a weird response for the caller (we don't
-// expect it after all), or maybe a range that was not exactly what it was asked
-// for.
-//
-// If the server is simply telling us that the resource has changed, we delete
-// the cached entry and restart the request as the caller intended (by returning
-// false from this method). However, we may not be able to do that at any point,
-// for instance if we already returned the headers to the user.
-//
-// WARNING: Whenever this code returns false, it has to make sure that the next
-// time it is called it will return true so that we don't keep retrying the
-// request.
-bool HttpCache::Transaction::ValidatePartialResponse() {
-  const HttpResponseHeaders* headers = new_response_->headers.get();
-  int response_code = headers->response_code();
-  bool partial_response = (response_code == 206);
-  handling_206_ = false;
-
-  if (!entry_ || request_->method != "GET")
-    return true;
-
-  if (invalid_range_) {
-    // We gave up trying to match this request with the stored data. If the
-    // server is ok with the request, delete the entry, otherwise just ignore
-    // this request
-    DCHECK(!reading_);
-    if (partial_response || response_code == 200) {
-      DoomPartialEntry(true);
-      mode_ = NONE;
-    } else {
-      if (response_code == 304)
-        FailRangeRequest();
-      IgnoreRangeRequest();
-    }
-    return true;
-  }
-
-  if (!partial_.get()) {
-    // We are not expecting 206 but we may have one.
-    if (partial_response)
-      IgnoreRangeRequest();
-
-    return true;
-  }
-
-  // TODO(rvargas): Do we need to consider other results here?.
-  bool failure = response_code == 200 || response_code == 416;
-
-  if (partial_->IsCurrentRangeCached()) {
-    // We asked for "If-None-Match: " so a 206 means a new object.
-    if (partial_response)
-      failure = true;
-
-    if (response_code == 304 && partial_->ResponseHeadersOK(headers))
-      return true;
-  } else {
-    // We asked for "If-Range: " so a 206 means just another range.
-    if (partial_response) {
-      if (partial_->ResponseHeadersOK(headers)) {
-        handling_206_ = true;
-        return true;
-      } else {
-        failure = true;
-      }
-    }
-
-    if (!reading_ && !is_sparse_ && !partial_response) {
-      // See if we can ignore the fact that we issued a byte range request.
-      // If the server sends 200, just store it. If it sends an error, redirect
-      // or something else, we may store the response as long as we didn't have
-      // anything already stored.
-      if (response_code == 200 ||
-          (!truncated_ && response_code != 304 && response_code != 416)) {
-        // The server is sending something else, and we can save it.
-        DCHECK((truncated_ && !partial_->IsLastRange()) || range_requested_);
-        partial_.reset();
-        truncated_ = false;
-        return true;
-      }
-    }
-
-    // 304 is not expected here, but we'll spare the entry (unless it was
-    // truncated).
-    if (truncated_)
-      failure = true;
-  }
-
-  if (failure) {
-    // We cannot truncate this entry, it has to be deleted.
-    UpdateTransactionPattern(PATTERN_NOT_COVERED);
-    mode_ = NONE;
-    if (is_sparse_ || truncated_) {
-      // There was something cached to start with, either sparsed data (206), or
-      // a truncated 200, which means that we probably modified the request,
-      // adding a byte range or modifying the range requested by the caller.
-      if (!reading_ && !partial_->IsLastRange()) {
-        // We have not returned anything to the caller yet so it should be safe
-        // to issue another network request, this time without us messing up the
-        // headers.
-        ResetPartialState(true);
-        return false;
-      }
-      LOG(WARNING) << "Failed to revalidate partial entry";
-    }
-    DoomPartialEntry(true);
-    return true;
-  }
-
-  IgnoreRangeRequest();
-  return true;
-}
-
-void HttpCache::Transaction::IgnoreRangeRequest() {
-  // We have a problem. We may or may not be reading already (in which case we
-  // returned the headers), but we'll just pretend that this request is not
-  // using the cache and see what happens. Most likely this is the first
-  // response from the server (it's not changing its mind midway, right?).
-  UpdateTransactionPattern(PATTERN_NOT_COVERED);
-  if (mode_ & WRITE)
-    DoneWritingToEntry(mode_ != WRITE);
-  else if (mode_ & READ && entry_)
-    cache_->DoneReadingFromEntry(entry_, this);
-
-  partial_.reset(NULL);
-  entry_ = NULL;
-  mode_ = NONE;
-}
-
-void HttpCache::Transaction::FixHeadersForHead() {
-  if (response_.headers->response_code() == 206) {
-    response_.headers->RemoveHeader("Content-Range");
-    response_.headers->ReplaceStatusLine("HTTP/1.1 200 OK");
-  }
-}
-
-void HttpCache::Transaction::TriggerAsyncValidation() {
-  DCHECK(!request_->upload_data_stream);
-  BoundNetLog async_revalidation_net_log(
-      BoundNetLog::Make(net_log_.net_log(), NetLog::SOURCE_ASYNC_REVALIDATION));
-  net_log_.AddEvent(
-      NetLog::TYPE_HTTP_CACHE_VALIDATE_RESOURCE_ASYNC,
-      async_revalidation_net_log.source().ToEventParametersCallback());
-  async_revalidation_net_log.BeginEvent(
-      NetLog::TYPE_ASYNC_REVALIDATION,
-      base::Bind(
-          &NetLogAsyncRevalidationInfoCallback, net_log_.source(), request_));
-  base::MessageLoop::current()->PostTask(
-      FROM_HERE,
-      base::Bind(&HttpCache::PerformAsyncValidation,
-                 cache_,  // cache_ is a weak pointer.
-                 *request_,
-                 async_revalidation_net_log));
-}
-
-void HttpCache::Transaction::FailRangeRequest() {
-  response_ = *new_response_;
-  partial_->FixResponseHeaders(response_.headers.get(), false);
-}
-
-int HttpCache::Transaction::SetupEntryForRead() {
-  if (network_trans_)
-    ResetNetworkTransaction();
-  if (partial_.get()) {
-    if (truncated_ || is_sparse_ || !invalid_range_) {
-      // We are going to return the saved response headers to the caller, so
-      // we may need to adjust them first.
-      next_state_ = STATE_PARTIAL_HEADERS_RECEIVED;
-      return OK;
-    } else {
-      partial_.reset();
-    }
-  }
-  cache_->ConvertWriterToReader(entry_);
-  mode_ = READ;
-
-  if (request_->method == "HEAD")
-    FixHeadersForHead();
-
-  if (entry_->disk_entry->GetDataSize(kMetadataIndex))
-    next_state_ = STATE_CACHE_READ_METADATA;
-  return OK;
-}
-
-
-int HttpCache::Transaction::ReadFromNetwork(IOBuffer* data, int data_len) {
-  read_buf_ = data;
-  io_buf_len_ = data_len;
-  next_state_ = STATE_NETWORK_READ;
-  return DoLoop(OK);
-}
-
-int HttpCache::Transaction::ReadFromEntry(IOBuffer* data, int data_len) {
-  if (request_->method == "HEAD")
-    return 0;
-
-  read_buf_ = data;
-  io_buf_len_ = data_len;
-  next_state_ = STATE_CACHE_READ_DATA;
-  return DoLoop(OK);
-}
-
-int HttpCache::Transaction::WriteToEntry(int index, int offset,
-                                         IOBuffer* data, int data_len,
-                                         const CompletionCallback& callback) {
-  if (!entry_)
-    return data_len;
-
-  int rv = 0;
-  if (!partial_.get() || !data_len) {
-    rv = entry_->disk_entry->WriteData(index, offset, data, data_len, callback,
-                                       true);
-  } else {
-    rv = partial_->CacheWrite(entry_->disk_entry, data, data_len, callback);
-  }
-  return rv;
-}
-
-int HttpCache::Transaction::WriteResponseInfoToEntry(bool truncated) {
-  next_state_ = STATE_CACHE_WRITE_RESPONSE_COMPLETE;
-  if (!entry_)
-    return OK;
-
-  // Do not cache no-store content (unless we are record mode).  Do not cache
-  // content with cert errors either.  This is to prevent not reporting net
-  // errors when loading a resource from the cache.  When we load a page over
-  // HTTPS with a cert error we show an SSL blocking page.  If the user clicks
-  // proceed we reload the resource ignoring the errors.  The loaded resource
-  // is then cached.  If that resource is subsequently loaded from the cache,
-  // no net error is reported (even though the cert status contains the actual
-  // errors) and no SSL blocking page is shown.  An alternative would be to
-  // reverse-map the cert status to a net error and replay the net error.
-  if ((cache_->mode() != RECORD &&
-       response_.headers->HasHeaderValue("cache-control", "no-store")) ||
-      net::IsCertStatusError(response_.ssl_info.cert_status)) {
-    DoneWritingToEntry(false);
-    if (net_log_.IsLogging())
-      net_log_.EndEvent(NetLog::TYPE_HTTP_CACHE_WRITE_INFO);
-    return OK;
-  }
-
-  // cert_cache() will be null if the CertCacheTrial field trial is disabled.
-  if (cache_->cert_cache() && response_.ssl_info.is_valid())
-    WriteCertChain();
-
-  // When writing headers, we normally only write the non-transient
-  // headers; when in record mode, record everything.
-  bool skip_transient_headers = (cache_->mode() != RECORD);
-
-  if (truncated)
-    DCHECK_EQ(200, response_.headers->response_code());
-
-  scoped_refptr<PickledIOBuffer> data(new PickledIOBuffer());
-  response_.Persist(data->pickle(), skip_transient_headers, truncated);
-  data->Done();
-
-  io_buf_len_ = data->pickle()->size();
-  return entry_->disk_entry->WriteData(kResponseInfoIndex, 0, data.get(),
-                                       io_buf_len_, io_callback_, true);
-}
-
-int HttpCache::Transaction::AppendResponseDataToEntry(
-    IOBuffer* data, int data_len, const CompletionCallback& callback) {
-  if (!entry_ || !data_len)
-    return data_len;
-
-  int current_size = entry_->disk_entry->GetDataSize(kResponseContentIndex);
-  return WriteToEntry(kResponseContentIndex, current_size, data, data_len,
-                      callback);
-}
-
-void HttpCache::Transaction::DoneWritingToEntry(bool success) {
-  if (!entry_)
-    return;
-
-  RecordHistograms();
-
-  cache_->DoneWritingToEntry(entry_, success);
-  entry_ = NULL;
-  mode_ = NONE;  // switch to 'pass through' mode
-}
-
-int HttpCache::Transaction::OnCacheReadError(int result, bool restart) {
-  DLOG(ERROR) << "ReadData failed: " << result;
-  const int result_for_histogram = std::max(0, -result);
-  if (restart) {
-    UMA_HISTOGRAM_SPARSE_SLOWLY("HttpCache.ReadErrorRestartable",
-                                result_for_histogram);
-  } else {
-    UMA_HISTOGRAM_SPARSE_SLOWLY("HttpCache.ReadErrorNonRestartable",
-                                result_for_histogram);
-  }
-
-  // Avoid using this entry in the future.
-  if (cache_.get())
-    cache_->DoomActiveEntry(cache_key_);
-
-  if (restart) {
-    DCHECK(!reading_);
-    DCHECK(!network_trans_.get());
-    cache_->DoneWithEntry(entry_, this, false);
-    entry_ = NULL;
-    is_sparse_ = false;
-    partial_.reset();
-    next_state_ = STATE_GET_BACKEND;
-    return OK;
-  }
-
-  return ERR_CACHE_READ_FAILURE;
-}
-
-void HttpCache::Transaction::OnAddToEntryTimeout(base::TimeTicks start_time) {
-  if (entry_lock_waiting_since_ != start_time)
-    return;
-
-  DCHECK_EQ(next_state_, STATE_ADD_TO_ENTRY_COMPLETE);
-
-  if (!cache_)
-    return;
-
-  cache_->RemovePendingTransaction(this);
-  OnIOComplete(ERR_CACHE_LOCK_TIMEOUT);
-}
-
-void HttpCache::Transaction::DoomPartialEntry(bool delete_object) {
-  DVLOG(2) << "DoomPartialEntry";
-  int rv = cache_->DoomEntry(cache_key_, NULL);
-  DCHECK_EQ(OK, rv);
-  cache_->DoneWithEntry(entry_, this, false);
-  entry_ = NULL;
-  is_sparse_ = false;
-  truncated_ = false;
-  if (delete_object)
-    partial_.reset(NULL);
-}
-
-int HttpCache::Transaction::DoPartialNetworkReadCompleted(int result) {
-  partial_->OnNetworkReadCompleted(result);
-
-  if (result == 0) {
-    // We need to move on to the next range.
-    ResetNetworkTransaction();
-    next_state_ = STATE_START_PARTIAL_CACHE_VALIDATION;
-  }
-  return result;
-}
-
-int HttpCache::Transaction::DoPartialCacheReadCompleted(int result) {
-  partial_->OnCacheReadCompleted(result);
-
-  if (result == 0 && mode_ == READ_WRITE) {
-    // We need to move on to the next range.
-    next_state_ = STATE_START_PARTIAL_CACHE_VALIDATION;
-  } else if (result < 0) {
-    return OnCacheReadError(result, false);
-  }
-  return result;
-}
-
-int HttpCache::Transaction::DoRestartPartialRequest() {
-  // The stored data cannot be used. Get rid of it and restart this request.
-  net_log_.AddEvent(NetLog::TYPE_HTTP_CACHE_RESTART_PARTIAL_REQUEST);
-
-  // WRITE + Doom + STATE_INIT_ENTRY == STATE_CREATE_ENTRY (without an attempt
-  // to Doom the entry again).
-  mode_ = WRITE;
-  ResetPartialState(!range_requested_);
-  next_state_ = STATE_CREATE_ENTRY;
-  return OK;
-}
-
-void HttpCache::Transaction::ResetPartialState(bool delete_object) {
-  partial_->RestoreHeaders(&custom_request_->extra_headers);
-  DoomPartialEntry(delete_object);
-
-  if (!delete_object) {
-    // The simplest way to re-initialize partial_ is to create a new object.
-    partial_.reset(new PartialData());
-    if (partial_->Init(request_->extra_headers))
-      partial_->SetHeaders(custom_request_->extra_headers);
-    else
-      partial_.reset();
-  }
-}
-
-void HttpCache::Transaction::ResetNetworkTransaction() {
-  DCHECK(!old_network_trans_load_timing_);
-  DCHECK(network_trans_);
-  LoadTimingInfo load_timing;
-  if (network_trans_->GetLoadTimingInfo(&load_timing))
-    old_network_trans_load_timing_.reset(new LoadTimingInfo(load_timing));
-  total_received_bytes_ += network_trans_->GetTotalReceivedBytes();
-  network_trans_.reset();
-}
-
-// Histogram data from the end of 2010 show the following distribution of
-// response headers:
-//
-//   Content-Length............... 87%
-//   Date......................... 98%
-//   Last-Modified................ 49%
-//   Etag......................... 19%
-//   Accept-Ranges: bytes......... 25%
-//   Accept-Ranges: none.......... 0.4%
-//   Strong Validator............. 50%
-//   Strong Validator + ranges.... 24%
-//   Strong Validator + CL........ 49%
-//
-bool HttpCache::Transaction::CanResume(bool has_data) {
-  // Double check that there is something worth keeping.
-  if (has_data && !entry_->disk_entry->GetDataSize(kResponseContentIndex))
-    return false;
-
-  if (request_->method != "GET")
-    return false;
-
-  // Note that if this is a 206, content-length was already fixed after calling
-  // PartialData::ResponseHeadersOK().
-  if (response_.headers->GetContentLength() <= 0 ||
-      response_.headers->HasHeaderValue("Accept-Ranges", "none") ||
-      !response_.headers->HasStrongValidators()) {
-    return false;
-  }
-
-  return true;
-}
-
-void HttpCache::Transaction::UpdateTransactionPattern(
-    TransactionPattern new_transaction_pattern) {
-  if (transaction_pattern_ == PATTERN_NOT_COVERED)
-    return;
-  DCHECK(transaction_pattern_ == PATTERN_UNDEFINED ||
-         new_transaction_pattern == PATTERN_NOT_COVERED);
-  transaction_pattern_ = new_transaction_pattern;
-}
-
-void HttpCache::Transaction::RecordHistograms() {
-  DCHECK_NE(PATTERN_UNDEFINED, transaction_pattern_);
-  if (!cache_.get() || !cache_->GetCurrentBackend() ||
-      cache_->GetCurrentBackend()->GetCacheType() != DISK_CACHE ||
-      cache_->mode() != NORMAL || request_->method != "GET") {
-    return;
-  }
-  UMA_HISTOGRAM_ENUMERATION(
-      "HttpCache.Pattern", transaction_pattern_, PATTERN_MAX);
-  if (transaction_pattern_ == PATTERN_NOT_COVERED)
-    return;
-  DCHECK(!range_requested_);
-  DCHECK(!first_cache_access_since_.is_null());
-
-  TimeDelta total_time = base::TimeTicks::Now() - first_cache_access_since_;
-
-  UMA_HISTOGRAM_TIMES("HttpCache.AccessToDone", total_time);
-
-  bool did_send_request = !send_request_since_.is_null();
-  DCHECK(
-      (did_send_request &&
-       (transaction_pattern_ == PATTERN_ENTRY_NOT_CACHED ||
-        transaction_pattern_ == PATTERN_ENTRY_VALIDATED ||
-        transaction_pattern_ == PATTERN_ENTRY_UPDATED ||
-        transaction_pattern_ == PATTERN_ENTRY_CANT_CONDITIONALIZE)) ||
-      (!did_send_request && transaction_pattern_ == PATTERN_ENTRY_USED));
-
-  if (!did_send_request) {
-    DCHECK(transaction_pattern_ == PATTERN_ENTRY_USED);
-    UMA_HISTOGRAM_TIMES("HttpCache.AccessToDone.Used", total_time);
-    return;
-  }
-
-  TimeDelta before_send_time = send_request_since_ - first_cache_access_since_;
-  int64 before_send_percent = (total_time.ToInternalValue() == 0) ?
-      0 : before_send_time * 100 / total_time;
-  DCHECK_GE(before_send_percent, 0);
-  DCHECK_LE(before_send_percent, 100);
-  base::HistogramBase::Sample before_send_sample =
-      static_cast<base::HistogramBase::Sample>(before_send_percent);
-
-  UMA_HISTOGRAM_TIMES("HttpCache.AccessToDone.SentRequest", total_time);
-  UMA_HISTOGRAM_TIMES("HttpCache.BeforeSend", before_send_time);
-  UMA_HISTOGRAM_PERCENTAGE("HttpCache.PercentBeforeSend", before_send_sample);
-
-  // TODO(gavinp): Remove or minimize these histograms, particularly the ones
-  // below this comment after we have received initial data.
-  switch (transaction_pattern_) {
-    case PATTERN_ENTRY_CANT_CONDITIONALIZE: {
-      UMA_HISTOGRAM_TIMES("HttpCache.BeforeSend.CantConditionalize",
-                          before_send_time);
-      UMA_HISTOGRAM_PERCENTAGE("HttpCache.PercentBeforeSend.CantConditionalize",
-                               before_send_sample);
-      break;
-    }
-    case PATTERN_ENTRY_NOT_CACHED: {
-      UMA_HISTOGRAM_TIMES("HttpCache.BeforeSend.NotCached", before_send_time);
-      UMA_HISTOGRAM_PERCENTAGE("HttpCache.PercentBeforeSend.NotCached",
-                               before_send_sample);
-      break;
-    }
-    case PATTERN_ENTRY_VALIDATED: {
-      UMA_HISTOGRAM_TIMES("HttpCache.BeforeSend.Validated", before_send_time);
-      UMA_HISTOGRAM_PERCENTAGE("HttpCache.PercentBeforeSend.Validated",
-                               before_send_sample);
-      break;
-    }
-    case PATTERN_ENTRY_UPDATED: {
-      UMA_HISTOGRAM_TIMES("HttpCache.BeforeSend.Updated", before_send_time);
-      UMA_HISTOGRAM_PERCENTAGE("HttpCache.PercentBeforeSend.Updated",
-                               before_send_sample);
-      break;
-    }
-    default:
-      NOTREACHED();
-  }
-}
-
-void HttpCache::Transaction::OnIOComplete(int result) {
-  // TODO(vadimt): Remove ScopedTracker below once crbug.com/422516 is fixed.
-  tracked_objects::ScopedTracker tracking_profile(
-      FROM_HERE_WITH_EXPLICIT_FUNCTION("422516 Transaction::OnIOComplete"));
-
-  DoLoop(result);
-}
-
-}  // namespace net