Separate BufferedDataSource and BufferedResourceLoader into two files.

webkit/glue/media/buffered_data_source.cc

 // Copyright (c) 2010 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 "base/callback.h"
-#include "base/compiler_specific.h"
-#include "base/format_macros.h"
-#include "base/message_loop.h"
-#include "base/process_util.h"
-#include "base/stl_util-inl.h"
-#include "base/string_number_conversions.h"
-#include "base/string_util.h"
+#include "webkit/glue/media/buffered_data_source.h"
+
 #include "media/base/filter_host.h"
-#include "media/base/media_format.h"
-#include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
-#include "third_party/WebKit/WebKit/chromium/public/WebKit.h"
-#include "third_party/WebKit/WebKit/chromium/public/WebKitClient.h"
-#include "third_party/WebKit/WebKit/chromium/public/WebString.h"
-#include "third_party/WebKit/WebKit/chromium/public/WebURLError.h"
-#include "webkit/glue/media/buffered_data_source.h"
-#include "webkit/glue/multipart_response_delegate.h"
+#include "net/http/http_util.h"
 #include "webkit/glue/webkit_glue.h"
-#include "webkit/glue/webmediaplayer_impl.h"
 
 using WebKit::WebFrame;
-using WebKit::WebString;
-using WebKit::WebURLError;
-using WebKit::WebURLLoader;
-using WebKit::WebURLRequest;
-using WebKit::WebURLResponse;
-using webkit_glue::MultipartResponseDelegate;
-
-namespace {
-
-const char kHttpScheme[] = "http";
-const char kHttpsScheme[] = "https";
-const char kDataScheme[] = "data";
-const int64 kPositionNotSpecified = -1;
-const int kHttpOK = 200;
-const int kHttpPartialContent = 206;
-
-// Define the number of bytes in a megabyte.
-const size_t kMegabyte = 1024 * 1024;
-
-// Backward capacity of the buffer, by default 2MB.
-const size_t kBackwardCapcity = 2 * kMegabyte;
-
-// Forward capacity of the buffer, by default 10MB.
-const size_t kForwardCapacity = 10 * kMegabyte;
-
-// The threshold of bytes that we should wait until the data arrives in the
-// future instead of restarting a new connection. This number is defined in the
-// number of bytes, we should determine this value from typical connection speed
-// and amount of time for a suitable wait. Now I just make a guess for this
-// number to be 2MB.
-// TODO(hclam): determine a better value for this.
-const int kForwardWaitThreshold = 2 * kMegabyte;
-
-// Defines how long we should wait for more data before we declare a connection
-// timeout and start a new request.
-// TODO(hclam): Set it to 5s, calibrate this value later.
-const int kTimeoutMilliseconds = 5000;
-
-// Defines how many times we should try to read from a buffered resource loader
-// before we declare a read error. After each failure of read from a buffered
-// resource loader, a new one is created to be read.
-const int kReadTrials = 3;
-
-// BufferedDataSource has an intermediate buffer, this value governs the initial
-// size of that buffer. It is set to 32KB because this is a typical read size
-// of FFmpeg.
-const int kInitialReadBufferSize = 32768;
-
-// Returns true if |url| operates on HTTP protocol.
-bool IsHttpProtocol(const GURL& url) {
-  return url.SchemeIs(kHttpScheme) || url.SchemeIs(kHttpsScheme);
-}
-
-bool IsDataProtocol(const GURL& url) {
-  return url.SchemeIs(kDataScheme);
-}
-
-}  // namespace
+using net::HttpUtil;

[scherkus (not reviewing), 2010/12/14 18:48:19]

nit: alphabetize forward declares

[annacc, 2010/12/14 21:10:17]

Done.

 
 namespace webkit_glue {
 
-/////////////////////////////////////////////////////////////////////////////
-// BufferedResourceLoader
-BufferedResourceLoader::BufferedResourceLoader(
-    const GURL& url,
-    int64 first_byte_position,
-    int64 last_byte_position)
-    : buffer_(new media::SeekableBuffer(kBackwardCapcity, kForwardCapacity)),
-      deferred_(false),
-      defer_allowed_(true),
-      completed_(false),
-      range_requested_(false),
-      partial_response_(false),
-      url_(url),
-      first_byte_position_(first_byte_position),
-      last_byte_position_(last_byte_position),
-      start_callback_(NULL),
-      offset_(0),
-      content_length_(kPositionNotSpecified),
-      instance_size_(kPositionNotSpecified),
-      read_callback_(NULL),
-      read_position_(0),
-      read_size_(0),
-      read_buffer_(NULL),
-      first_offset_(0),
-      last_offset_(0),
-      keep_test_loader_(false) {
-}
-
-BufferedResourceLoader::~BufferedResourceLoader() {
-  if (!completed_ && url_loader_.get())
-    url_loader_->cancel();
-}
-
-void BufferedResourceLoader::Start(net::CompletionCallback* start_callback,
-                                   NetworkEventCallback* event_callback,
-                                   WebFrame* frame) {
-  // Make sure we have not started.
-  DCHECK(!start_callback_.get());
-  DCHECK(!event_callback_.get());
-  DCHECK(start_callback);
-  DCHECK(event_callback);
-  CHECK(frame);
-
-  start_callback_.reset(start_callback);
-  event_callback_.reset(event_callback);
-
-  if (first_byte_position_ != kPositionNotSpecified) {
-    range_requested_ = true;
-    // TODO(hclam): server may not support range request so |offset_| may not
-    // equal to |first_byte_position_|.
-    offset_ = first_byte_position_;
-  }
-
-  // Increment the reference count right before we start the request. This
-  // reference will be release when this request has ended.
-  AddRef();
-
-  // Prepare the request.
-  WebURLRequest request(url_);
-  request.setHTTPHeaderField(WebString::fromUTF8("Range"),
-                             WebString::fromUTF8(GenerateHeaders(
-                                                 first_byte_position_,
-                                                 last_byte_position_)));
-  frame->setReferrerForRequest(request, WebKit::WebURL());
-  // TODO(annacc): we should be using createAssociatedURLLoader() instead?
-  frame->dispatchWillSendRequest(request);
-
-  // This flag is for unittests as we don't want to reset |url_loader|
-  if (!keep_test_loader_)
-    url_loader_.reset(WebKit::webKitClient()->createURLLoader());
-
-  // Start the resource loading.
-  url_loader_->loadAsynchronously(request, this);
-}
-
-void BufferedResourceLoader::Stop() {
-  // Reset callbacks.
-  start_callback_.reset();
-  event_callback_.reset();
-  read_callback_.reset();
-
-  // Use the internal buffer to signal that we have been stopped.
-  // TODO(hclam): Not so pretty to do this.
-  if (!buffer_.get())
-    return;
-
-  // Destroy internal buffer.
-  buffer_.reset();
-
-  if (url_loader_.get()) {
-    if (deferred_)
-      url_loader_->setDefersLoading(false);
-    deferred_ = false;
-
-    if (!completed_) {
-      url_loader_->cancel();
-      completed_ = true;
-    }
-  }
-}
-
-void BufferedResourceLoader::Read(int64 position,
-                                  int read_size,
-                                  uint8* buffer,
-                                  net::CompletionCallback* read_callback) {
-  DCHECK(!read_callback_.get());
-  DCHECK(buffer_.get());
-  DCHECK(read_callback);
-  DCHECK(buffer);
-
-  // Save the parameter of reading.
-  read_callback_.reset(read_callback);
-  read_position_ = position;
-  read_size_ = read_size;
-  read_buffer_ = buffer;
-
-  // If read position is beyond the instance size, we cannot read there.
-  if (instance_size_ != kPositionNotSpecified &&
-      instance_size_ <= read_position_) {
-    DoneRead(0);
-    return;
-  }
-
-  // Make sure |offset_| and |read_position_| does not differ by a large
-  // amount.
-  if (read_position_ > offset_ + kint32max ||
-      read_position_ < offset_ + kint32min) {
-    DoneRead(net::ERR_CACHE_MISS);
-    return;
-  }
-
-  // Prepare the parameters.
-  first_offset_ = static_cast<int>(read_position_ - offset_);
-  last_offset_ = first_offset_ + read_size_;
-
-  // If we can serve the request now, do the actual read.
-  if (CanFulfillRead()) {
-    ReadInternal();
-    DisableDeferIfNeeded();
-    return;
-  }
-
-  // If we expected the read request to be fulfilled later, returns
-  // immediately and let more data to flow in.
-  if (WillFulfillRead())
-    return;
-
-  // Make a callback to report failure.
-  DoneRead(net::ERR_CACHE_MISS);
-}
-
-int64 BufferedResourceLoader::GetBufferedFirstBytePosition() {
-  if (buffer_.get())
-    return offset_ - static_cast<int>(buffer_->backward_bytes());
-  return kPositionNotSpecified;
-}
-
-int64 BufferedResourceLoader::GetBufferedLastBytePosition() {
-  if (buffer_.get())
-    return offset_ + static_cast<int>(buffer_->forward_bytes()) - 1;
-  return kPositionNotSpecified;
-}
-
-void BufferedResourceLoader::SetAllowDefer(bool is_allowed) {
-  defer_allowed_ = is_allowed;
-  DisableDeferIfNeeded();
-}
-
-void BufferedResourceLoader::SetURLLoaderForTest(WebURLLoader* mock_loader) {
-  url_loader_.reset(mock_loader);
-  keep_test_loader_ = true;
-}
-
-/////////////////////////////////////////////////////////////////////////////
-// BufferedResourceLoader, WebKit::WebURLLoaderClient implementations.
-void BufferedResourceLoader::willSendRequest(
-    WebURLLoader* loader,
-    WebURLRequest& newRequest,
-    const WebURLResponse& redirectResponse) {
-
-  // The load may have been stopped and |start_callback| is destroyed.
-  // In this case we shouldn't do anything.
-  if (!start_callback_.get()) {
-    // Set the url in the request to an invalid value (empty url).
-    newRequest.setURL(WebKit::WebURL());
-    return;
-  }
-
-  if (!IsProtocolSupportedForMedia(newRequest.url())) {
-    // Set the url in the request to an invalid value (empty url).
-    newRequest.setURL(WebKit::WebURL());
-    DoneStart(net::ERR_ADDRESS_INVALID);
-    Stop();
-    return;
-  }
-
-  url_ = newRequest.url();
-}
-
-void BufferedResourceLoader::didSendData(
-    WebURLLoader* loader,
-    unsigned long long bytes_sent,
-    unsigned long long total_bytes_to_be_sent) {
-  NOTIMPLEMENTED();
-}
-
-void BufferedResourceLoader::didReceiveResponse(
-    WebURLLoader* loader,
-    const WebURLResponse& response) {
-
-  // The loader may have been stopped and |start_callback| is destroyed.
-  // In this case we shouldn't do anything.
-  if (!start_callback_.get())
-    return;
-
-  // We make a strong assumption that when we reach here we have either
-  // received a response from HTTP/HTTPS protocol or the request was
-  // successful (in particular range request). So we only verify the partial
-  // response for HTTP and HTTPS protocol.
-  if (IsHttpProtocol(url_)) {
-    int error = net::OK;
-
-    if (response.httpStatusCode() == kHttpPartialContent)
-      partial_response_ = true;
-
-    if (range_requested_ && partial_response_) {
-      // If we have verified the partial response and it is correct, we will
-      // return net::OK.
-      if (!VerifyPartialResponse(response))
-        error = net::ERR_INVALID_RESPONSE;
-    } else if (response.httpStatusCode() != kHttpOK) {
-      // We didn't request a range but server didn't reply with "200 OK".
-      error = net::ERR_FAILED;
-    }
-
-    if (error != net::OK) {
-      DoneStart(error);
-      Stop();
-      return;
-    }
-  } else {
-    // For any protocol other than HTTP and HTTPS, assume range request is
-    // always fulfilled.
-    partial_response_ = range_requested_;
-  }
-
-  // Expected content length can be -1, in that case |content_length_| is
-  // not specified and this is a streaming response.
-  content_length_ = response.expectedContentLength();
-
-  // If we have not requested a range, then the size of the instance is equal
-  // to the content length.
-  if (!partial_response_)
-    instance_size_ = content_length_;
-
-  // Calls with a successful response.
-  DoneStart(net::OK);
-}
-
-void BufferedResourceLoader::didReceiveData(
-    WebURLLoader* loader,
-    const char* data,
-    int data_length) {
-  DCHECK(!completed_);
-  DCHECK_GT(data_length, 0);
-
-  // If this loader has been stopped, |buffer_| would be destroyed.
-  // In this case we shouldn't do anything.
-  if (!buffer_.get())
-    return;
-
-  // Writes more data to |buffer_|.
-  buffer_->Append(reinterpret_cast<const uint8*>(data), data_length);
-
-  // If there is an active read request, try to fulfill the request.
-  if (HasPendingRead() && CanFulfillRead()) {
-    ReadInternal();
-  } else if (!defer_allowed_) {
-    // If we're not allowed to defer, slide the buffer window forward instead
-    // of deferring.
-    if (buffer_->forward_bytes() > buffer_->forward_capacity()) {
-      size_t excess = buffer_->forward_bytes() - buffer_->forward_capacity();
-      bool success = buffer_->Seek(excess);
-      DCHECK(success);
-      offset_ += first_offset_ + excess;
-    }
-  }
-
-  // At last see if the buffer is full and we need to defer the downloading.
-  EnableDeferIfNeeded();
-
-  // Notify that we have received some data.
-  NotifyNetworkEvent();
-}
-
-void BufferedResourceLoader::didDownloadData(
-    WebKit::WebURLLoader* loader,
-    int dataLength) {
-  NOTIMPLEMENTED();
-}
-
-void BufferedResourceLoader::didReceiveCachedMetadata(
-    WebURLLoader* loader,
-    const char* data,
-    int data_length) {
-  NOTIMPLEMENTED();
-}
-
-void BufferedResourceLoader::didFinishLoading(
-    WebURLLoader* loader,
-    double finishTime) {
-  DCHECK(!completed_);
-  completed_ = true;
-
-  // If there is a start callback, calls it.
-  if (start_callback_.get()) {
-    DoneStart(net::OK);
-  }
-
-  // If there is a pending read but the request has ended, returns with what
-  // we have.
-  if (HasPendingRead()) {
-    // Make sure we have a valid buffer before we satisfy a read request.
-    DCHECK(buffer_.get());
-
-    // Try to fulfill with what is in the buffer.
-    if (CanFulfillRead())
-      ReadInternal();
-    else
-      DoneRead(net::ERR_CACHE_MISS);
-  }
-
-  // There must not be any outstanding read request.
-  DCHECK(!HasPendingRead());
-
-  // Notify that network response is completed.
-  NotifyNetworkEvent();
-
-  url_loader_.reset();
-  Release();
-}
-
-void BufferedResourceLoader::didFail(
-    WebURLLoader* loader,
-    const WebURLError& error) {
-  DCHECK(!completed_);
-  completed_ = true;
-
-  // If there is a start callback, calls it.
-  if (start_callback_.get()) {
-    DoneStart(error.reason);
-  }
-
-  // If there is a pending read but the request failed, return with the
-  // reason for the error.
-  if (HasPendingRead()) {
-    DoneRead(error.reason);
-  }
-
-  // Notify that network response is completed.
-  NotifyNetworkEvent();
-
-  url_loader_.reset();
-  Release();
-}
-
-/////////////////////////////////////////////////////////////////////////////
-// BufferedResourceLoader, private
-void BufferedResourceLoader::EnableDeferIfNeeded() {
-  if (!defer_allowed_)
-    return;
-
-  if (!deferred_ &&
-      buffer_->forward_bytes() >= buffer_->forward_capacity()) {
-    deferred_ = true;
-
-  if (url_loader_.get())
-    url_loader_->setDefersLoading(true);
-
-    NotifyNetworkEvent();
-  }
-}
-
-void BufferedResourceLoader::DisableDeferIfNeeded() {
-  if (deferred_ &&
-      (!defer_allowed_ ||
-       buffer_->forward_bytes() < buffer_->forward_capacity() / 2)) {
-    deferred_ = false;
-
-    if (url_loader_.get())
-      url_loader_->setDefersLoading(false);
-
-    NotifyNetworkEvent();
-  }
-}
-
-bool BufferedResourceLoader::CanFulfillRead() {
-  // If we are reading too far in the backward direction.
-  if (first_offset_ < 0 &&
-      first_offset_ + static_cast<int>(buffer_->backward_bytes()) < 0)
-    return false;
-
-  // If the start offset is too far ahead.
-  if (first_offset_ >= static_cast<int>(buffer_->forward_bytes()))
-    return false;
-
-  // At the point, we verified that first byte requested is within the buffer.
-  // If the request has completed, then just returns with what we have now.
-  if (completed_)
-    return true;
-
-  // If the resource request is still active, make sure the whole requested
-  // range is covered.
-  if (last_offset_ > static_cast<int>(buffer_->forward_bytes()))
-    return false;
-
-  return true;
-}
-
-bool BufferedResourceLoader::WillFulfillRead() {
-  // Reading too far in the backward direction.
-  if (first_offset_ < 0 &&
-      first_offset_ + static_cast<int>(buffer_->backward_bytes()) < 0)
-    return false;
-
-  // Try to read too far ahead.
-  if (last_offset_ > kForwardWaitThreshold)
-    return false;
-
-  // The resource request has completed, there's no way we can fulfill the
-  // read request.
-  if (completed_)
-    return false;
-
-  return true;
-}
-
-void BufferedResourceLoader::ReadInternal() {
-  // Seek to the first byte requested.
-  bool ret = buffer_->Seek(first_offset_);
-  DCHECK(ret);
-
-  // Then do the read.
-  int read = static_cast<int>(buffer_->Read(read_buffer_, read_size_));
-  offset_ += first_offset_ + read;
-
-  // And report with what we have read.
-  DoneRead(read);
-}
-
-bool BufferedResourceLoader::VerifyPartialResponse(
-    const WebURLResponse& response) {
-  int first_byte_position, last_byte_position, instance_size;
-
-  if (!MultipartResponseDelegate::ReadContentRanges(response,
-                         &first_byte_position,
-                         &last_byte_position,
-                         &instance_size)) {
-    return false;
-  }
-
-  if (instance_size != kPositionNotSpecified) {
-    instance_size_ = instance_size;
-  }
-
-  if (first_byte_position_ != kPositionNotSpecified &&
-      first_byte_position_ != first_byte_position) {
-    return false;
-  }
-
-  // TODO(hclam): I should also check |last_byte_position|, but since
-  // we will never make such a request that it is ok to leave it unimplemented.
-  return true;
-}
-
-std::string BufferedResourceLoader::GenerateHeaders(
-    int64 first_byte_position,
-    int64 last_byte_position) {
-  // Construct the value for the range header.
-  std::string header;
-  if (first_byte_position > kPositionNotSpecified &&
-      last_byte_position > kPositionNotSpecified) {
-    if (first_byte_position <= last_byte_position) {
-      header = base::StringPrintf("bytes=%" PRId64 "-%" PRId64,
-                                  first_byte_position,
-                                  last_byte_position);
-    }
-  } else if (first_byte_position > kPositionNotSpecified) {
-    header = base::StringPrintf("bytes=%" PRId64 "-",
-                                first_byte_position);
-  } else if (last_byte_position > kPositionNotSpecified) {
-    NOTIMPLEMENTED() << "Suffix range not implemented";
-  }
-  return header;
-}
-
-void BufferedResourceLoader::DoneRead(int error) {
-  read_callback_->RunWithParams(Tuple1<int>(error));
-  read_callback_.reset();
-  read_position_ = 0;
-  read_size_ = 0;
-  read_buffer_ = NULL;
-  first_offset_ = 0;
-  last_offset_ = 0;
-}
-
-void BufferedResourceLoader::DoneStart(int error) {
-  start_callback_->RunWithParams(Tuple1<int>(error));
-  start_callback_.reset();
-}
-
-void BufferedResourceLoader::NotifyNetworkEvent() {
-  if (event_callback_.get())
-    event_callback_->Run();
-}
-
-/////////////////////////////////////////////////////////////////////////////
-// BufferedDataSource
 BufferedDataSource::BufferedDataSource(
     MessageLoop* render_loop,
     WebFrame* frame)
-    : total_bytes_(kPositionNotSpecified),
+    : total_bytes_(net::kPositionNotSpecified),
       loaded_(false),
       streaming_(false),
       frame_(frame),
       single_origin_(true),
       loader_(NULL),
       network_activity_(false),
       initialize_callback_(NULL),
       read_callback_(NULL),
       read_position_(0),
       read_size_(0),
       read_buffer_(NULL),
       read_attempts_(0),
-      intermediate_read_buffer_(new uint8[kInitialReadBufferSize]),
-      intermediate_read_buffer_size_(kInitialReadBufferSize),
+      intermediate_read_buffer_(new uint8[net::kInitialReadBufferSize]),
+      intermediate_read_buffer_size_(net::kInitialReadBufferSize),
       render_loop_(render_loop),
       stop_signal_received_(false),
       stopped_on_render_loop_(false),
       media_is_paused_(true),
       using_range_request_(true) {
 }
 
 BufferedDataSource::~BufferedDataSource() {
 }
 
 // A factory method to create BufferedResourceLoader using the read parameters.
 // This method can be overrided to inject mock BufferedResourceLoader object
 // for testing purpose.
 BufferedResourceLoader* BufferedDataSource::CreateResourceLoader(
     int64 first_byte_position, int64 last_byte_position) {
   DCHECK(MessageLoop::current() == render_loop_);
 
   return new BufferedResourceLoader(url_,
                                     first_byte_position,
                                     last_byte_position);
 }
 
 // This method simply returns kTimeoutMilliseconds. The purpose of this
 // method is to be overidded so as to provide a different timeout value
 // for testing purpose.
 base::TimeDelta BufferedDataSource::GetTimeoutMilliseconds() {
-  return base::TimeDelta::FromMilliseconds(kTimeoutMilliseconds);
+  return base::TimeDelta::FromMilliseconds(net::kTimeoutMilliseconds);
 }
 
 /////////////////////////////////////////////////////////////////////////////
 // BufferedDataSource, media::Filter implementation
 void BufferedDataSource::Initialize(const std::string& url,
                                     media::FilterCallback* callback) {
   // Saves the url.
   url_ = GURL(url);
 
   if (!IsProtocolSupportedForMedia(url_)) {
@@ skipping 14 matching lines @@
 
   // Post a task to complete the initialization task.
   render_loop_->PostTask(FROM_HERE,
       NewRunnableMethod(this, &BufferedDataSource::InitializeTask));
 }
 
 bool BufferedDataSource::IsUrlSupported(const std::string& url) {
   GURL gurl(url);
 
   // This data source doesn't support data:// protocol so reject it.
-  return IsProtocolSupportedForMedia(gurl) && !IsDataProtocol(gurl);
+  return IsProtocolSupportedForMedia(gurl) && !net::HttpUtil::IsDataProtocol(gurl);

[annacc, 2010/12/14 21:10:17]

Done.

 }
 
 void BufferedDataSource::Stop(media::FilterCallback* callback) {
   {
     AutoLock auto_lock(lock_);
     stop_signal_received_ = true;
   }
   if (callback) {
     callback->Run();
     delete callback;
@@ skipping 12 matching lines @@
 /////////////////////////////////////////////////////////////////////////////
 // BufferedDataSource, media::DataSource implementation
 void BufferedDataSource::Read(int64 position, size_t size, uint8* data,
                               media::DataSource::ReadCallback* read_callback) {
   render_loop_->PostTask(FROM_HERE,
       NewRunnableMethod(this, &BufferedDataSource::ReadTask,
                         position, static_cast<int>(size), data, read_callback));
 }
 
 bool BufferedDataSource::GetSize(int64* size_out) {
-  if (total_bytes_ != kPositionNotSpecified) {
+  if (total_bytes_ != net::kPositionNotSpecified) {
     *size_out = total_bytes_;
     return true;
   }
   *size_out = 0;
   return false;
 }
 
 bool BufferedDataSource::IsStreaming() {
   return streaming_;
 }
@@ skipping 26 matching lines @@
     return;
 
   // Kick starts the watch dog task that will handle connection timeout.
   // We run the watch dog 2 times faster the actual timeout so as to catch
   // the timeout more accurately.
   watch_dog_timer_.Start(
       GetTimeoutMilliseconds() / 2,
       this,
       &BufferedDataSource::WatchDogTask);
 
-  if (IsHttpProtocol(url_)) {
+  if (net::HttpUtil::IsHttpProtocol(url_)) {
     // Fetch only first 1024 bytes as this usually covers the header portion
     // of a media file that gives enough information about the codecs, etc.
     // This also serve as a probe to determine server capability to serve
     // range request.
     // TODO(hclam): Do some experiments for the best approach.
     loader_ = CreateResourceLoader(0, 1024);
     loader_->Start(
         NewCallback(this, &BufferedDataSource::HttpInitialStartCallback),
         NewCallback(this, &BufferedDataSource::NetworkEventCallback),
         frame_);
@@ skipping 81 matching lines @@
   if (!read_callback_.get())
     return;
 
   DCHECK(loader_.get());
   base::TimeDelta delta = base::Time::Now() - read_submitted_time_;
   if (delta < GetTimeoutMilliseconds())
     return;
 
   // TODO(hclam): Maybe raise an error here. But if an error is reported
   // the whole pipeline may get destroyed...
-  if (read_attempts_ >= kReadTrials)
+  if (read_attempts_ >= net::kReadTrials)
     return;
 
   ++read_attempts_;
   read_submitted_time_ = base::Time::Now();
 
   // Stops the current loader and creates a new resource loader and
   // retry the request.
   loader_->Stop();
   loader_ = CreateResourceLoader(read_position_, -1);
   loader_->SetAllowDefer(!media_is_paused_);
@@ skipping 78 matching lines @@
 
   int64 instance_size = loader_->instance_size();
   bool partial_response = loader_->partial_response();
   bool success = error == net::OK;
 
   if (success) {
     // TODO(hclam): Needs more thinking about supporting servers without range
     // request or their partial response is not complete.
     total_bytes_ = instance_size;
     loaded_ = false;
-    streaming_ = (instance_size == kPositionNotSpecified) || !partial_response;
+    streaming_ = (instance_size == net::kPositionNotSpecified) || !partial_response;

[annacc, 2010/12/14 21:10:17]

Done.

   } else {
     // TODO(hclam): In case of failure, we can retry several times.
     loader_->Stop();
   }
 
   if (error == net::ERR_INVALID_RESPONSE && using_range_request_) {
     // Assuming that the Range header was causing the problem. Retry without
     // the Range header.
     using_range_request_ = false;
     loader_ = CreateResourceLoader(-1, -1);
@@ skipping 39 matching lines @@
 }
 
 void BufferedDataSource::NonHttpInitialStartCallback(int error) {
   DCHECK(MessageLoop::current() == render_loop_);
   DCHECK(loader_.get());
 
   // Check if the request ended up at a different origin via redirect.
   single_origin_ = url_.GetOrigin() == loader_->url().GetOrigin();
 
   int64 instance_size = loader_->instance_size();
-  bool success = error == net::OK && instance_size != kPositionNotSpecified;
+  bool success = error == net::OK && instance_size != net::kPositionNotSpecified;
 
   if (success) {
     total_bytes_ = instance_size;
     loaded_ = true;
   } else {
     loader_->Stop();
   }
 
   // We need to prevent calling to filter host and running the callback if
   // we have received the stop signal. We need to lock down the whole callback
@@ skipping 90 matching lines @@
 
   // In case of non-HTTP request we don't need to report network events,
   // so return immediately.
   if (loaded_)
     return;
 
   bool network_activity = loader_->network_activity();
   int64 buffered_last_byte_position = loader_->GetBufferedLastBytePosition();
 
   // If we get an unspecified value, return immediately.
-  if (buffered_last_byte_position == kPositionNotSpecified)
+  if (buffered_last_byte_position == net::kPositionNotSpecified)
     return;
 
   // We need to prevent calling to filter host and running the callback if
   // we have received the stop signal. We need to lock down the whole callback
   // method to prevent bad things from happening. The reason behind this is
   // that we cannot guarantee tasks on render thread have completely stopped
   // when we receive the Stop() method call. So only way to solve this is to
   // let tasks on render thread to run but make sure they don't call outside
   // this object when Stop() method is ever called. Locking this method is safe
   // because |lock_| is only acquired in tasks on render thread.
   AutoLock auto_lock(lock_);
   if (stop_signal_received_)
     return;
 
   if (network_activity != network_activity_) {
     network_activity_ = network_activity;
     host()->SetNetworkActivity(network_activity);
   }
   host()->SetBufferedBytes(buffered_last_byte_position + 1);
 }
 
 }  // namespace webkit_glue