[cast] Add optional VideoEncoder method to flush frames.

media/cast/sender/h264_vt_encoder.h

 // Copyright 2014 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.
 
 #ifndef MEDIA_CAST_SENDER_H264_VT_ENCODER_H_
 #define MEDIA_CAST_SENDER_H264_VT_ENCODER_H_
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/mac/videotoolbox_glue.h"
@@ skipping 18 matching lines @@
 
   // media::cast::VideoEncoder implementation
   bool EncodeVideoFrame(
       const scoped_refptr<media::VideoFrame>& video_frame,
       const base::TimeTicks& reference_time,
       const FrameEncodedCallback& frame_encoded_callback) override;
   void SetBitRate(int new_bit_rate) override;
   void GenerateKeyFrame() override;
   void LatestFrameIdToReference(uint32 frame_id) override;
   scoped_ptr<VideoFrameFactory> CreateVideoFrameFactory() override;
+  void EmitFrames() override;
 
  private:
   // Initialize the compression session.
   bool Initialize(const VideoSenderConfig& video_config);
 
   // Configure the compression session.
   void ConfigureSession(const VideoSenderConfig& video_config);
 
   // Teardown the encoder.
   void Teardown();
@@ skipping 28 matching lines @@
   // Force next frame to be a keyframe.
   bool encode_next_frame_as_keyframe_;
 
   DISALLOW_COPY_AND_ASSIGN(H264VideoToolboxEncoder);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_SENDER_H264_VT_ENCODER_H_