Add power monitoring to the Cast VideoToolbox encoder.

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/power_monitor/power_observer.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/mac/videotoolbox_glue.h"
 #include "media/cast/sender/size_adaptable_video_encoder_base.h"
 #include "media/cast/sender/video_encoder.h"
 
 namespace media {
 namespace cast {
 
 // VideoToolbox implementation of the media::cast::VideoEncoder interface.
 // VideoToolbox makes no guarantees that it is thread safe, so this object is
 // pinned to the thread on which it is constructed. Supports changing frame
-// sizes directly.
-class H264VideoToolboxEncoder : public VideoEncoder {
+// sizes directly. Implements the base::PowerObserver interface to reset the
+// compression session when the host process is suspended.
+class H264VideoToolboxEncoder : public VideoEncoder,
+                                public base::PowerObserver {
   typedef CoreMediaGlue::CMSampleBufferRef CMSampleBufferRef;
   typedef VideoToolboxGlue::VTCompressionSessionRef VTCompressionSessionRef;
   typedef VideoToolboxGlue::VTEncodeInfoFlags VTEncodeInfoFlags;
 
  public:
   // Returns true if the current platform and system configuration supports
   // using H264VideoToolboxEncoder with the given |video_config|.
   static bool IsSupported(const VideoSenderConfig& video_config);
 
   H264VideoToolboxEncoder(
       const scoped_refptr<CastEnvironment>& cast_environment,
       const VideoSenderConfig& video_config,
       const StatusChangeCallback& status_change_cb);
   ~H264VideoToolboxEncoder() override;
 
   // 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;
 
+  // base::PowerObserver
+  void OnSuspend() override;
+  void OnResume() override;
+
  private:
   // VideoFrameFactory tied to the VideoToolbox encoder.
   class VideoFrameFactoryImpl;
 
   // Reset the encoder's compression session by destroying the existing one
   // using DestroyCompressionSession() and creating a new one. The new session
   // is configured using ConfigureCompressionSession().
   void ResetCompressionSession();
 
   // Configure the current compression session using current encoder settings.
@@ skipping 56 matching lines @@
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<H264VideoToolboxEncoder> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(H264VideoToolboxEncoder);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_SENDER_H264_VT_ENCODER_H_