Introduce CancelUponDeferral() to buffered media loaders.

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index 93f3bd43cf20d7f92c05ff5cc423e3a716159334..3d0557e9be4e5e59879f2faaef0bbd1cd6362929 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -789,8 +789,7 @@ void WebMediaPlayerImpl::OnPipelineMetadata(
 
   pipeline_metadata_ = metadata;
 
-  UMA_HISTOGRAM_ENUMERATION("Media.VideoRotation",
-                            metadata.video_rotation,
+  UMA_HISTOGRAM_ENUMERATION("Media.VideoRotation", metadata.video_rotation,
                             VIDEO_ROTATION_MAX + 1);
   SetReadyState(WebMediaPlayer::ReadyStateHaveMetadata);
 
@@ -824,6 +823,14 @@ void WebMediaPlayerImpl::OnPipelineBufferingStateChanged(
   DCHECK_EQ(buffering_state, BUFFERING_HAVE_ENOUGH);
   SetReadyState(WebMediaPlayer::ReadyStateHaveEnoughData);
 
+  // If we were only tasked to preload and a play request hasn't come in yet,
+  // cancel the DataSource once it reaches the deferred state if it isn't
+  // already. Subsequent play requests will restart the DataSource.
+  if (preload_ == BufferedDataSource::METADATA && data_source_ &&
+      !data_source_->IsStreaming() && !data_source_->media_has_played()) {
+    data_source_->CancelUponDeferral();
+  }

[xhwang, 2015/03/26 07:21:55]

Seems like |data_source_| knows the preload type, IsStreaming() and
media_has_played(), can we move these logic to |data_source_|?

e.g.

if (data_source_)
  data_source_->OnBufferingHaveEnough();

[DaleCurtis, 2015/03/26 17:22:00]

Great idea!

+
   // Blink expects a timeChanged() in response to a seek().
   if (should_notify_time_changed_)
     client_->timeChanged();