ServiceWorkerWriteToCacheJob: refactor

content/browser/service_worker/service_worker_write_to_cache_job.cc

Index: content/browser/service_worker/service_worker_write_to_cache_job.cc
diff --git a/content/browser/service_worker/service_worker_write_to_cache_job.cc b/content/browser/service_worker/service_worker_write_to_cache_job.cc
index 781a65257b61f1371eb8eaa703cdae73565c3dd0..ca801ca39c9bb713962fdc6a93ba9c2366603945 100644
--- a/content/browser/service_worker/service_worker_write_to_cache_job.cc
+++ b/content/browser/service_worker/service_worker_write_to_cache_job.cc
@@ -4,10 +4,11 @@
 
 #include "content/browser/service_worker/service_worker_write_to_cache_job.h"
 
-#include <algorithm>
-
+#include "base/bind.h"
+#include "base/callback.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
+#include "content/browser/service_worker/service_worker_cache_writer.h"
 #include "content/browser/service_worker/service_worker_context_core.h"
 #include "content/browser/service_worker/service_worker_disk_cache.h"
 #include "content/browser/service_worker/service_worker_metrics.h"
@@ -18,7 +19,6 @@
 #include "net/http/http_network_session.h"
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
-#include "net/http/http_util.h"
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_status.h"
@@ -40,260 +40,8 @@ const char kRedirectError[] =
     "The script resource is behind a redirect, which is disallowed.";
 const char kServiceWorkerAllowed[] = "Service-Worker-Allowed";
 
-const int kBufferSize = 16 * 1024;
-
 }  // namespace
 
-// Reads an existing resource and copies it via
-// ServiceWorkerWriteToCacheJob::WriteData.
-class ServiceWorkerWriteToCacheJob::Copier : public base::RefCounted<Copier> {
- public:
-  Copier(base::WeakPtr<ServiceWorkerWriteToCacheJob> owner,
-         scoped_ptr<ServiceWorkerResponseReader> reader,
-         int bytes_to_copy,
-         const base::Callback<void(ServiceWorkerStatusCode)>& callback)
-      : owner_(owner),
-        reader_(reader.release()),
-        bytes_to_copy_(bytes_to_copy),
-        callback_(callback) {
-    DCHECK_LT(0, bytes_to_copy_);
-  }
-
-  void Start() {
-    io_buffer_ = new net::IOBuffer(kBufferSize);
-    ReadSomeData();
-  }
-
- private:
-  friend class base::RefCounted<Copier>;
-  ~Copier() {}
-
-  void ReadSomeData() {
-    reader_->ReadData(io_buffer_.get(), kBufferSize,
-                      base::Bind(&Copier::OnReadDataComplete, this));
-  }
-
-  void OnReadDataComplete(int result) {
-    if (!owner_)
-      return;
-    if (result <= 0) {
-      // We hit EOF or error but weren't done copying.
-      Complete(SERVICE_WORKER_ERROR_FAILED);
-      return;
-    }
-
-    int bytes_to_write = std::min(bytes_to_copy_, result);
-    owner_->WriteData(io_buffer_.get(), bytes_to_write,
-                      base::Bind(&Copier::OnWriteDataComplete, this));
-  }
-
-  void OnWriteDataComplete(int result) {
-    if (result < 0) {
-      Complete(SERVICE_WORKER_ERROR_FAILED);
-      return;
-    }
-
-    DCHECK_LE(result, bytes_to_copy_);
-    bytes_to_copy_ -= result;
-    if (bytes_to_copy_ == 0) {
-      Complete(SERVICE_WORKER_OK);
-      return;
-    }
-
-    ReadSomeData();
-  }
-
-  void Complete(ServiceWorkerStatusCode status) {
-    if (!owner_)
-      return;
-    callback_.Run(status);
-  }
-
-  base::WeakPtr<ServiceWorkerWriteToCacheJob> owner_;
-  scoped_ptr<ServiceWorkerResponseReader> reader_;
-  int bytes_to_copy_ = 0;
-  base::Callback<void(ServiceWorkerStatusCode)> callback_;
-  scoped_refptr<net::IOBuffer> io_buffer_;
-};
-
-// Abstract consumer for ServiceWorkerWriteToCacheJob that processes data from
-// the network.
-class ServiceWorkerWriteToCacheJob::NetDataConsumer {
- public:
-  virtual ~NetDataConsumer() {}
-
-  // Called by |owner_|'s OnResponseStarted.
-  virtual void OnResponseStarted() = 0;
-
-  // HandleData should call |owner_|->NotifyReadComplete() when done.
-  virtual void HandleData(net::IOBuffer* buf, int size) = 0;
-};
-
-// Dumb consumer that just writes everything it sees to disk.
-class ServiceWorkerWriteToCacheJob::PassThroughConsumer
-    : public ServiceWorkerWriteToCacheJob::NetDataConsumer {
- public:
-  explicit PassThroughConsumer(ServiceWorkerWriteToCacheJob* owner)
-      : owner_(owner), weak_factory_(this) {}
-  ~PassThroughConsumer() override {}
-
-  void OnResponseStarted() override {
-    owner_->WriteHeaders(
-        base::Bind(&PassThroughConsumer::OnWriteHeadersComplete,
-                   weak_factory_.GetWeakPtr()));
-    owner_->SetPendingIO();
-  }
-
-  void HandleData(net::IOBuffer* buf, int size) override {
-    if (size == 0) {
-      owner_->OnPassThroughComplete();
-      return;
-    }
-
-    owner_->WriteData(buf, size,
-                      base::Bind(&PassThroughConsumer::OnWriteDataComplete,
-                                 weak_factory_.GetWeakPtr()));
-    owner_->SetPendingIO();
-  }
-
- private:
-  void OnWriteHeadersComplete() {
-    owner_->ClearPendingIO();
-    owner_->CommitHeadersAndNotifyHeadersComplete();
-  }
-
-  void OnWriteDataComplete(int result) {
-    owner_->ClearPendingIO();
-    owner_->NotifyReadComplete(result);
-  }
-
-  ServiceWorkerWriteToCacheJob* owner_;
-  base::WeakPtrFactory<PassThroughConsumer> weak_factory_;
-};
-
-// Compares an existing resource with data progressively fed to it.
-// Calls back to |owner|->OnCompareComplete once done.
-class ServiceWorkerWriteToCacheJob::Comparer
-    : public ServiceWorkerWriteToCacheJob::NetDataConsumer {
- public:
-  Comparer(ServiceWorkerWriteToCacheJob* owner,
-           scoped_ptr<ServiceWorkerResponseReader> reader)
-      : owner_(owner), reader_(reader.release()), weak_factory_(this) {}
-  ~Comparer() override {}
-
-  void OnResponseStarted() override {
-    owner_->CommitHeadersAndNotifyHeadersComplete();
-  }
-
-  void HandleData(net::IOBuffer* buf, int size) override {
-    net_data_ = buf;
-    net_data_offset_ = 0;
-    net_data_size_ = size;
-
-    if (size == 0 && info_) {
-      Complete(bytes_matched_ == info_->response_data_size);
-      return;
-    }
-
-    if (!info_) {
-      read_buffer_ = new net::IOBuffer(kBufferSize);
-      info_ = new HttpResponseInfoIOBuffer;
-      reader_->ReadInfo(info_.get(), base::Bind(&Comparer::OnReadInfoComplete,
-                                                weak_factory_.GetWeakPtr()));
-      owner_->SetPendingIO();
-      return;
-    }
-
-    ReadSomeData();
-    owner_->SetPendingIO();
-  }
-
- private:
-  int bytes_remaining() {
-    DCHECK(net_data_);
-    DCHECK_LE(0, net_data_offset_);
-    DCHECK_LE(net_data_offset_, net_data_size_);
-    return net_data_size_ - net_data_offset_;
-  }
-
-  void OnReadInfoComplete(int result) {
-    if (result < 0) {
-      Complete(false);
-      return;
-    }
-
-    if (bytes_remaining() == 0) {
-      Complete(bytes_matched_ == info_->response_data_size);
-      return;
-    }
-
-    ReadSomeData();
-  }
-
-  void ReadSomeData() {
-    DCHECK_LT(0, bytes_remaining());
-    int bytes_to_read = std::min(bytes_remaining(), kBufferSize);
-    reader_->ReadData(
-        read_buffer_.get(), bytes_to_read,
-        base::Bind(&Comparer::OnReadDataComplete, weak_factory_.GetWeakPtr()));
-  }
-
-  void OnReadDataComplete(int result) {
-    if (result <= 0) {
-      // We hit error or EOF but had more to compare.
-      Complete(false);
-      return;
-    }
-
-    DCHECK_LE(result, bytes_remaining());
-    if (memcmp(net_data_->data() + net_data_offset_, read_buffer_->data(),
-               result) != 0) {
-      Complete(false);
-      return;
-    }
-
-    net_data_offset_ += result;
-    if (bytes_remaining() == 0) {
-      NotifyReadComplete();
-      return;
-    }
-
-    ReadSomeData();
-  }
-
-  // Completes one HandleData() call.
-  void NotifyReadComplete() {
-    int size = net_data_size_;
-    net_data_ = nullptr;
-    net_data_offset_ = 0;
-    net_data_size_ = 0;
-
-    bytes_matched_ += size;
-    owner_->ClearPendingIO();
-    owner_->NotifyReadComplete(size);
-  }
-
-  // Completes the entire Comparer.
-  void Complete(bool is_equal) {
-    owner_->OnCompareComplete(bytes_matched_, is_equal);
-  }
-
-  ServiceWorkerWriteToCacheJob* owner_;
-  scoped_ptr<ServiceWorkerResponseReader> reader_;
-  scoped_refptr<net::IOBuffer> read_buffer_;
-  scoped_refptr<HttpResponseInfoIOBuffer> info_;
-
-  // Cumulative number of bytes successfully compared.
-  int bytes_matched_ = 0;
-
-  // State used for one HandleData() call.
-  scoped_refptr<net::IOBuffer> net_data_;
-  int net_data_offset_ = 0;
-  int net_data_size_ = 0;
-
-  base::WeakPtrFactory<Comparer> weak_factory_;
-};
-
 ServiceWorkerWriteToCacheJob::ServiceWorkerWriteToCacheJob(
     net::URLRequest* request,
     net::NetworkDelegate* network_delegate,
@@ -331,14 +79,14 @@ void ServiceWorkerWriteToCacheJob::Start() {
         net::URLRequestStatus::FAILED, net::ERR_FAILED));
     return;
   }
-  if (incumbent_response_id_ != kInvalidServiceWorkerResourceId) {
-    scoped_ptr<ServiceWorkerResponseReader> incumbent_reader =
-        context_->storage()->CreateResponseReader(incumbent_response_id_);
-    consumer_.reset(new Comparer(this, incumbent_reader.Pass()));
-  } else {
-    consumer_.reset(new PassThroughConsumer(this));
-  }
 
+  // These uses of Unretained are safe because this object is the sole owner of
+  // |cache_writer_|, which in turn is the sole user of these callbacks.
+  cache_writer_.reset(new ServiceWorkerCacheWriter(
+      base::Bind(&ServiceWorkerWriteToCacheJob::CreateCacheResponseReader,
+                 base::Unretained(this)),
+      base::Bind(&ServiceWorkerWriteToCacheJob::CreateCacheResponseWriter,
+                 base::Unretained(this))));
   version_->script_cache_map()->NotifyStartedCaching(
       url_, response_id_);
   did_notify_started_ = true;
@@ -351,12 +99,9 @@ void ServiceWorkerWriteToCacheJob::Kill() {
   weak_factory_.InvalidateWeakPtrs();
   has_been_killed_ = true;
   net_request_.reset();
-  if (did_notify_started_ && !did_notify_finished_) {
-    version_->script_cache_map()->NotifyFinishedCaching(
-        url_, -1,
-        net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_ABORTED),
-        kKilledError);
-    did_notify_finished_ = true;
+  if (did_notify_started_) {
+    NotifyFinishedCaching(net::URLRequestStatus::FromError(net::ERR_ABORTED),
+                          kKilledError);
   }
   writer_.reset();
   context_.reset();
@@ -412,17 +157,21 @@ bool ServiceWorkerWriteToCacheJob::ReadRawData(net::IOBuffer* buf,
     return false;
 
   if (!status.is_success()) {
-    AsyncNotifyDoneHelper(status, kFetchScriptError);
+    NotifyDoneHelper(status, kFetchScriptError);
     return false;
   }
 
-  DCHECK_EQ(0, *bytes_read);
-  consumer_->HandleData(buf, 0);
-  if (did_notify_finished_)
-    return GetStatus().is_success();
-  if (GetStatus().is_io_pending())
+  HandleNetData(*bytes_read);
+
+  if (!status.is_success()) {
+    NotifyDoneHelper(status, "");
     return false;
-  return status.is_success();
+  }
+
+  // Since URLRequestStatus::is_success() means "SUCCESS or IO_PENDING", but the
+  // contract of this function is "return true for synchronous successes only",
+  // it is important to test against SUCCESS explicitly here.
+  return GetStatus().status() == net::URLRequestStatus::SUCCESS;
 }
 
 const net::HttpResponseInfo* ServiceWorkerWriteToCacheJob::http_info() const {
@@ -461,104 +210,14 @@ net::URLRequestStatus ServiceWorkerWriteToCacheJob::ReadNetData(
     int* bytes_read) {
   DCHECK_GT(buf_size, 0);
   DCHECK(bytes_read);
-  *bytes_read = 0;
   io_buffer_ = buf;
   io_buffer_bytes_ = 0;
-  int net_bytes_read = 0;
-  if (!net_request_->Read(buf, buf_size, &net_bytes_read)) {
-    if (net_request_->status().is_io_pending())
-      return net_request_->status();
-    DCHECK(!net_request_->status().is_success());
-    return net_request_->status();
-  }
-
-  if (net_bytes_read != 0) {
-    HandleNetData(net_bytes_read);
-    DCHECK(GetStatus().is_io_pending());
-    return GetStatus();
-  }
+  if (!net_request_->Read(buf, buf_size, bytes_read))
+    DCHECK_NE(net::URLRequestStatus::SUCCESS, net_request_->status().status());
 
-  DCHECK(net_request_->status().is_success());
   return net_request_->status();
 }
 
-void ServiceWorkerWriteToCacheJob::WriteHeaders(const base::Closure& callback) {
-  if (!context_) {
-    AsyncNotifyDoneHelper(
-        net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED),
-        kFetchScriptError);
-    return;
-  }
-  TRACE_EVENT_ASYNC_STEP_INTO0("ServiceWorker",
-                               "ServiceWorkerWriteToCacheJob::ExecutingJob",
-                               this, "WriteHeaders");
-  writer_ = context_->storage()->CreateResponseWriter(response_id_);
-  scoped_refptr<HttpResponseInfoIOBuffer> info_buffer =
-      new HttpResponseInfoIOBuffer(
-          new net::HttpResponseInfo(net_request_->response_info()));
-  writer_->WriteInfo(
-      info_buffer.get(),
-      base::Bind(&ServiceWorkerWriteToCacheJob::OnWriteHeadersComplete,
-                 weak_factory_.GetWeakPtr(), callback));
-}
-
-void ServiceWorkerWriteToCacheJob::OnWriteHeadersComplete(
-    const base::Closure& callback,
-    int result) {
-  if (result < 0) {
-    ServiceWorkerMetrics::CountWriteResponseResult(
-        ServiceWorkerMetrics::WRITE_HEADERS_ERROR);
-    AsyncNotifyDoneHelper(
-        net::URLRequestStatus(net::URLRequestStatus::FAILED, result),
-        kFetchScriptError);
-    return;
-  }
-  TRACE_EVENT_ASYNC_STEP_INTO0("ServiceWorker",
-                               "ServiceWorkerWriteToCacheJob::ExecutingJob",
-                               this, "WriteHeadersCompleted");
-  callback.Run();
-}
-
-void ServiceWorkerWriteToCacheJob::WriteData(
-    net::IOBuffer* buf,
-    int bytes_to_write,
-    const base::Callback<void(int result)>& callback) {
-  DCHECK_LT(0, bytes_to_write);
-  TRACE_EVENT_ASYNC_STEP_INTO1(
-      "ServiceWorker", "ServiceWorkerWriteToCacheJob::ExecutingJob", this,
-      "WriteData", "Amount to write", bytes_to_write);
-
-  writer_->WriteData(
-      buf, bytes_to_write,
-      base::Bind(&ServiceWorkerWriteToCacheJob::OnWriteDataComplete,
-                 weak_factory_.GetWeakPtr(), callback));
-}
-
-void ServiceWorkerWriteToCacheJob::OnWriteDataComplete(
-    const base::Callback<void(int result)>& callback,
-    int result) {
-  DCHECK_NE(0, result);
-  if (!context_) {
-    AsyncNotifyDoneHelper(
-        net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED),
-        kFetchScriptError);
-    return;
-  }
-  if (result < 0) {
-    ServiceWorkerMetrics::CountWriteResponseResult(
-        ServiceWorkerMetrics::WRITE_DATA_ERROR);
-    AsyncNotifyDoneHelper(
-        net::URLRequestStatus(net::URLRequestStatus::FAILED, result),
-        kFetchScriptError);
-    return;
-  }
-  ServiceWorkerMetrics::CountWriteResponseResult(
-      ServiceWorkerMetrics::WRITE_OK);
-  callback.Run(result);
-  TRACE_EVENT_ASYNC_END0("ServiceWorker",
-                         "ServiceWorkerWriteToCacheJob::ExecutingJob", this);
-}
-
 void ServiceWorkerWriteToCacheJob::OnReceivedRedirect(
     net::URLRequest* request,
     const net::RedirectInfo& redirect_info,
@@ -567,9 +226,9 @@ void ServiceWorkerWriteToCacheJob::OnReceivedRedirect(
   TRACE_EVENT0("ServiceWorker",
                "ServiceWorkerWriteToCacheJob::OnReceivedRedirect");
   // Script resources can't redirect.
-  AsyncNotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
-                                              net::ERR_UNSAFE_REDIRECT),
-                        kRedirectError);
+  NotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
+                                         net::ERR_UNSAFE_REDIRECT),
+                   kRedirectError);
 }
 
 void ServiceWorkerWriteToCacheJob::OnAuthRequired(
@@ -579,7 +238,7 @@ void ServiceWorkerWriteToCacheJob::OnAuthRequired(
   TRACE_EVENT0("ServiceWorker",
                "ServiceWorkerWriteToCacheJob::OnAuthRequired");
   // TODO(michaeln): Pass this thru to our jobs client.
-  AsyncNotifyDoneHelper(
+  NotifyDoneHelper(
       net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED),
       kClientAuthenticationError);
 }
@@ -592,7 +251,7 @@ void ServiceWorkerWriteToCacheJob::OnCertificateRequested(
                "ServiceWorkerWriteToCacheJob::OnCertificateRequested");
   // TODO(michaeln): Pass this thru to our jobs client.
   // see NotifyCertificateRequested.
-  AsyncNotifyDoneHelper(
+  NotifyDoneHelper(
       net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED),
       kClientAuthenticationError);
 }
@@ -606,9 +265,9 @@ void ServiceWorkerWriteToCacheJob::OnSSLCertificateError(
                "ServiceWorkerWriteToCacheJob::OnSSLCertificateError");
   // TODO(michaeln): Pass this thru to our jobs client,
   // see NotifySSLCertificateError.
-  AsyncNotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
-                                              net::ERR_INSECURE_RESPONSE),
-                        kSSLError);
+  NotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
+                                         net::ERR_INSECURE_RESPONSE),
+                   kSSLError);
 }
 
 void ServiceWorkerWriteToCacheJob::OnBeforeNetworkStart(
@@ -624,15 +283,15 @@ void ServiceWorkerWriteToCacheJob::OnResponseStarted(
     net::URLRequest* request) {
   DCHECK_EQ(net_request_, request);
   if (!request->status().is_success()) {
-    AsyncNotifyDoneHelper(request->status(), kFetchScriptError);
+    NotifyDoneHelper(request->status(), kFetchScriptError);
     return;
   }
   if (request->GetResponseCode() / 100 != 2) {
     std::string error_message =
         base::StringPrintf(kBadHTTPResponseError, request->GetResponseCode());
-    AsyncNotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
-                                                net::ERR_INVALID_RESPONSE),
-                          error_message);
+    NotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
+                                           net::ERR_INVALID_RESPONSE),
+                     error_message);
     // TODO(michaeln): Instead of error'ing immediately, send the net
     // response to our consumer, just don't cache it?
     return;
@@ -643,9 +302,9 @@ void ServiceWorkerWriteToCacheJob::OnResponseStarted(
     const net::HttpNetworkSession::Params* session_params =
         request->context()->GetNetworkSessionParams();
     if (!session_params || !session_params->ignore_certificate_errors) {
-      AsyncNotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
-                                                  net::ERR_INSECURE_RESPONSE),
-                            kSSLError);
+      NotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
+                                             net::ERR_INSECURE_RESPONSE),
+                       kSSLError);
       return;
     }
   }
@@ -660,9 +319,9 @@ void ServiceWorkerWriteToCacheJob::OnResponseStarted(
           mime_type.empty()
               ? kNoMIMEError
               : base::StringPrintf(kBadMIMEError, mime_type.c_str());
-      AsyncNotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
-                                                  net::ERR_INSECURE_RESPONSE),
-                            error_message);
+      NotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
+                                             net::ERR_INSECURE_RESPONSE),
+                       error_message);
       return;
     }
 
@@ -675,17 +334,46 @@ void ServiceWorkerWriteToCacheJob::OnResponseStarted(
   if (net_request_->response_info().network_accessed)
     version_->embedded_worker()->OnNetworkAccessedForScriptLoad();
 
-  consumer_->OnResponseStarted();
+  http_info_.reset(new net::HttpResponseInfo(net_request_->response_info()));
+  scoped_refptr<HttpResponseInfoIOBuffer> info_buffer =
+      new HttpResponseInfoIOBuffer(
+          new net::HttpResponseInfo(net_request_->response_info()));
+  net::Error error = cache_writer_->MaybeWriteHeaders(
+      info_buffer.get(),
+      base::Bind(&ServiceWorkerWriteToCacheJob::OnWriteHeadersComplete,
+                 weak_factory_.GetWeakPtr()));
+  SetStatus(net::URLRequestStatus::FromError(error));
+  if (error != net::ERR_IO_PENDING)
+    NotifyHeadersComplete();
 }
 
-void ServiceWorkerWriteToCacheJob::CommitHeadersAndNotifyHeadersComplete() {
-  http_info_.reset(new net::HttpResponseInfo(net_request_->response_info()));
+void ServiceWorkerWriteToCacheJob::OnWriteHeadersComplete(net::Error error) {
+  SetStatus(net::URLRequestStatus::FromError(error));
   NotifyHeadersComplete();
 }
 
 void ServiceWorkerWriteToCacheJob::HandleNetData(int bytes_read) {
   io_buffer_bytes_ = bytes_read;
-  consumer_->HandleData(io_buffer_.get(), bytes_read);
+  net::Error error = cache_writer_->MaybeWriteData(
+      io_buffer_.get(), bytes_read,
+      base::Bind(&ServiceWorkerWriteToCacheJob::OnWriteDataComplete,
+                 weak_factory_.GetWeakPtr()));
+  SetStatus(net::URLRequestStatus::FromError(error));
+
+  // In case of ERR_IO_PENDING, this logic is done in OnWriteDataComplete.
+  if (error != net::ERR_IO_PENDING && bytes_read == 0) {
+    NotifyFinishedCaching(net::URLRequestStatus::FromError(error),
+                          std::string());
+  }
+}
+
+void ServiceWorkerWriteToCacheJob::OnWriteDataComplete(net::Error error) {
+  SetStatus(net::URLRequestStatus::FromError(error));
+  DCHECK_NE(net::ERR_IO_PENDING, error);
+  if (io_buffer_bytes_ == 0) {
+    NotifyDoneHelper(net::URLRequestStatus::FromError(error), std::string());
+  }
+  NotifyReadComplete(error == net::OK ? io_buffer_bytes_ : error);
 }
 
 void ServiceWorkerWriteToCacheJob::OnReadCompleted(
@@ -694,18 +382,23 @@ void ServiceWorkerWriteToCacheJob::OnReadCompleted(
   DCHECK_EQ(net_request_, request);
   if (bytes_read < 0) {
     DCHECK(!request->status().is_success());
-    AsyncNotifyDoneHelper(request->status(), kFetchScriptError);
+    NotifyDoneHelper(request->status(), kFetchScriptError);
     return;
   }
-  if (bytes_read > 0) {
-    HandleNetData(bytes_read);
-    DCHECK(GetStatus().is_io_pending());
-    return;
+  HandleNetData(bytes_read);
+  // HandleNetData can cause status of this job to change. If the status changes
+  // to IO_PENDING, that means HandleNetData has pending IO, and
+  // NotifyReadComplete will be called later by the appropriate callback.
+  if (!GetStatus().is_io_pending()) {
+    int result = GetStatus().status() == net::URLRequestStatus::SUCCESS
+                     ? bytes_read
+                     : GetStatus().error();
+    // If bytes_read is 0, HandleNetData synchronously completed and this job is
+    // at EOF.
+    if (bytes_read == 0)
+      NotifyDoneHelper(GetStatus(), std::string());
+    NotifyReadComplete(result);
   }
-
-  // No more data to process, the job is complete.
-  DCHECK(request->status().is_success());
-  HandleNetData(0);
 }
 
 bool ServiceWorkerWriteToCacheJob::CheckPathRestriction(
@@ -719,89 +412,15 @@ bool ServiceWorkerWriteToCacheJob::CheckPathRestriction(
   if (!ServiceWorkerUtils::IsPathRestrictionSatisfied(
           version_->scope(), url_,
           has_header ? &service_worker_allowed : nullptr, &error_message)) {
-    AsyncNotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
-                                                net::ERR_INSECURE_RESPONSE),
-                          error_message);
+    NotifyDoneHelper(net::URLRequestStatus(net::URLRequestStatus::FAILED,
+                                           net::ERR_INSECURE_RESPONSE),
+                     error_message);
     return false;
   }
   return true;
 }
 
-void ServiceWorkerWriteToCacheJob::SetPendingIO() {
-  SetStatus(net::URLRequestStatus(net::URLRequestStatus::IO_PENDING, 0));
-}
-
-void ServiceWorkerWriteToCacheJob::ClearPendingIO() {
-  SetStatus(net::URLRequestStatus());
-}
-
-void ServiceWorkerWriteToCacheJob::OnPassThroughComplete() {
-  NotifyFinishedCaching(net::URLRequestStatus(), std::string());
-  if (GetStatus().is_io_pending()) {
-    ClearPendingIO();
-    NotifyReadComplete(0);
-  }
-}
-
-void ServiceWorkerWriteToCacheJob::OnCompareComplete(int bytes_matched,
-                                                     bool is_equal) {
-  if (is_equal) {
-    // This version is identical to the incumbent, so discard it and fail this
-    // job.
-    version_->SetStartWorkerStatusCode(SERVICE_WORKER_ERROR_EXISTS);
-    AsyncNotifyDoneHelper(
-        net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED),
-        kFetchScriptError);
-    return;
-  }
-
-  // We must switch to the pass through consumer. Write what is known
-  // (headers + bytes matched) to disk.
-  WriteHeaders(base::Bind(&ServiceWorkerWriteToCacheJob::CopyIncumbent,
-                          weak_factory_.GetWeakPtr(), bytes_matched));
-  SetPendingIO();
-}
-
-void ServiceWorkerWriteToCacheJob::CopyIncumbent(int bytes_to_copy) {
-  if (bytes_to_copy == 0) {
-    OnCopyComplete(SERVICE_WORKER_OK);
-    return;
-  }
-  scoped_ptr<ServiceWorkerResponseReader> incumbent_reader =
-      context_->storage()->CreateResponseReader(incumbent_response_id_);
-  scoped_refptr<Copier> copier = new Copier(
-      weak_factory_.GetWeakPtr(), incumbent_reader.Pass(), bytes_to_copy,
-      base::Bind(&ServiceWorkerWriteToCacheJob::OnCopyComplete,
-                 weak_factory_.GetWeakPtr()));
-  copier->Start();  // It deletes itself when done.
-  DCHECK(GetStatus().is_io_pending());
-}
-
-void ServiceWorkerWriteToCacheJob::OnCopyComplete(
-    ServiceWorkerStatusCode status) {
-  if (status != SERVICE_WORKER_OK) {
-    AsyncNotifyDoneHelper(
-        net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED),
-        kFetchScriptError);
-    return;
-  }
-
-  // Continue processing the net data that triggered the comparison fail and
-  // copy.
-  if (io_buffer_bytes_ > 0) {
-    consumer_.reset(new PassThroughConsumer(this));
-    consumer_->HandleData(io_buffer_.get(), io_buffer_bytes_);
-    return;
-  }
-
-  // The copy was triggered by EOF from the network, which
-  // means the job is now done.
-  NotifyFinishedCaching(net::URLRequestStatus(), std::string());
-  ClearPendingIO();
-  NotifyReadComplete(0);
-}
-
-void ServiceWorkerWriteToCacheJob::AsyncNotifyDoneHelper(
+void ServiceWorkerWriteToCacheJob::NotifyDoneHelper(
     const net::URLRequestStatus& status,
     const std::string& status_message) {
   DCHECK(!status.is_io_pending());
@@ -813,13 +432,39 @@ void ServiceWorkerWriteToCacheJob::AsyncNotifyDoneHelper(
 void ServiceWorkerWriteToCacheJob::NotifyFinishedCaching(
     net::URLRequestStatus status,
     const std::string& status_message) {
-  DCHECK(!did_notify_finished_);
+  if (did_notify_finished_)
+    return;
+
+  // If all the calls to MaybeWriteHeaders/MaybeWriteData succeeded, but the
+  // incumbent entry wasn't actually replaced because the new entry was
+  // equivalent, the new version didn't actually install because it already
+  // exists.
+  if (status.status() == net::URLRequestStatus::SUCCESS &&
+      !cache_writer_->did_replace()) {
+    status =
+        net::URLRequestStatus(net::URLRequestStatus::FAILED, net::ERR_FAILED);
+    version_->SetStartWorkerStatusCode(SERVICE_WORKER_ERROR_EXISTS);
+  }
+
   int size = -1;
   if (status.is_success())
-    size = writer_ ? writer_->amount_written() : 0;
+    size = cache_writer_->bytes_written();
+
   version_->script_cache_map()->NotifyFinishedCaching(url_, size, status,
                                                       status_message);
   did_notify_finished_ = true;
 }
 
+scoped_ptr<ServiceWorkerResponseReader>
+ServiceWorkerWriteToCacheJob::CreateCacheResponseReader() {
+  if (incumbent_response_id_ != kInvalidServiceWorkerResponseId)
+    return context_->storage()->CreateResponseReader(incumbent_response_id_);
+  return nullptr;
+}
+
+scoped_ptr<ServiceWorkerResponseWriter>
+ServiceWorkerWriteToCacheJob::CreateCacheResponseWriter() {
+  return context_->storage()->CreateResponseWriter(response_id_);
+}
+
 }  // namespace content