Add power monitoring to the Cast VideoToolbox encoder.

media/cast/sender/h264_vt_encoder.h

Index: media/cast/sender/h264_vt_encoder.h
diff --git a/media/cast/sender/h264_vt_encoder.h b/media/cast/sender/h264_vt_encoder.h
index 7ae2f0545b337b24d733837cac06046c8d25209d..7a099b41336b4c781ea6f41e87e9167febdb4982 100644
--- a/media/cast/sender/h264_vt_encoder.h
+++ b/media/cast/sender/h264_vt_encoder.h
@@ -6,6 +6,7 @@
 #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"
@@ -24,9 +25,6 @@ class H264VideoToolboxEncoder : public VideoEncoder {
   typedef VideoToolboxGlue::VTEncodeInfoFlags VTEncodeInfoFlags;
 
  public:
-  // VideoFrameFactory tied to the VideoToolbox encoder.
-  class VideoFrameFactoryImpl;
-
   // Returns true if the current platform and system configuration supports
   // using H264VideoToolboxEncoder with the given |video_config|.
   static bool IsSupported(const VideoSenderConfig& video_config);
@@ -78,6 +76,24 @@ class H264VideoToolboxEncoder : public VideoEncoder {
                                   VTEncodeInfoFlags info,
                                   CMSampleBufferRef sbuf);
 
+  // VideoFrameFactory tied to the encoder.
+  class VideoFrameFactoryImpl;
+
+  // PowerObserver tied to the encoder. Emits all frames and destroys the
+  // compression session on suspend and resets the compression session on
+  // resume.
+  class PowerObserver : public base::PowerObserver {

[miu, 2015/04/22 04:02:58]

Instead of a nested class, how about making H264VideoToolboxEncoder extend
base::PowerObserver itself and implement the OnSuspend() and OnResume() methods?

[jfroy, 2015/04/22 04:18:45]

I considered that but decided to use an auxiliary class because of the rather
generic name of the interface methods.

I'll move the implementation directly in the encoder though since you seem to
prefer that.

+   public:
+    explicit PowerObserver(H264VideoToolboxEncoder* encoder);
+    virtual ~PowerObserver();
+    void OnSuspend() override;
+    void OnResume() override;
+
+   private:
+    H264VideoToolboxEncoder* encoder_;
+    DISALLOW_COPY_AND_ASSIGN(PowerObserver);
+  };
+
   // The cast environment (contains worker threads & more).
   const scoped_refptr<CastEnvironment> cast_environment_;
 
@@ -99,6 +115,9 @@ class H264VideoToolboxEncoder : public VideoEncoder {
   // Thread checker to enforce that this object is used on a specific thread.
   base::ThreadChecker thread_checker_;
 
+  // PowerObserver tied to the encoder.
+  const PowerObserver power_observer_;
+
   // The compression session.
   base::ScopedCFTypeRef<VTCompressionSessionRef> compression_session_;