Replace Pipeline::SetNetworkActivity() with BufferedDataSource -> WebMediaPlayerImpl callback.

webkit/media/buffered_data_source.h

Index: webkit/media/buffered_data_source.h
diff --git a/webkit/media/buffered_data_source.h b/webkit/media/buffered_data_source.h
index f151c5a95e3eff290f81a3c0055e1cdcf5751fa1..a3d251520b7ec7d557aa5d7d84cf4c7ba2ccbfe0 100644
--- a/webkit/media/buffered_data_source.h
+++ b/webkit/media/buffered_data_source.h
@@ -31,9 +31,12 @@ namespace webkit_media {
 // before being passed to other threads. It may be deleted on any thread.
 class BufferedDataSource : public media::DataSource {
  public:
+  typedef base::Callback<void(bool)> DownloadingCB;
+
   BufferedDataSource(MessageLoop* render_loop,
                      WebKit::WebFrame* frame,
-                     media::MediaLog* media_log);
+                     media::MediaLog* media_log,
+                     const DownloadingCB& downloading_cb);
 
   // Initialize this object using |url| and |cors_mode|, and call |status_cb|
   // when initialization has completed.
@@ -224,6 +227,8 @@ class BufferedDataSource : public media::DataSource {
 
   scoped_refptr<media::MediaLog> media_log_;
 
+  DownloadingCB downloading_cb_;
+
   DISALLOW_COPY_AND_ASSIGN(BufferedDataSource);
 };