Cast: Flow hw encoder initialization error to extensions API

media/cast/sender/video_sender.h

Index: media/cast/sender/video_sender.h
diff --git a/media/cast/sender/video_sender.h b/media/cast/sender/video_sender.h
index d2dfa45f4212fe33c687f62cedb4db91eaf72e58..86d1c815510652a0f2fe58a5caf383b221fd34c4 100644
--- a/media/cast/sender/video_sender.h
+++ b/media/cast/sender/video_sender.h
@@ -37,6 +37,7 @@ class VideoSender : public FrameSender,
  public:
   VideoSender(scoped_refptr<CastEnvironment> cast_environment,
               const VideoSenderConfig& video_config,
+              const CastInitializationCallback& initialization_cb,
               const CreateVideoEncodeAcceleratorCallback& create_vea_cb,
               const CreateVideoEncodeMemoryCallback& create_video_encode_mem_cb,
               CastTransportSender* const transport_sender);
@@ -70,6 +71,12 @@ class VideoSender : public FrameSender,
   // Called by the |video_encoder_| with the next EncodeFrame to send.
   void SendEncodedVideoFrame(int requested_bitrate_before_encode,
                              scoped_ptr<EncodedFrame> encoded_frame);
+
+  // Called when the encoder is initialized or has failed to initialize.
+  void OnEncoderInitialized(
+      const CastInitializationCallback& initialization_cb,
+      CastInitializationStatus status);
+
   // If this value is non zero then a fixed value is used for bitrate.
   // If external video encoder is used then bitrate will be fixed to
   // (min_bitrate + max_bitrate) / 2.