Cast: Fix threading issues in VideoEncoderImpl

media/cast/video_sender/video_encoder_impl.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_VIDEO_SENDER_VIDEO_ENCODER_IMPL_H_
 #define MEDIA_CAST_VIDEO_SENDER_VIDEO_ENCODER_IMPL_H_
 
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
 #include "media/cast/cast_config.h"
 #include "media/cast/cast_environment.h"
 #include "media/cast/video_sender/codecs/vp8/vp8_encoder.h"
 #include "media/cast/video_sender/video_encoder.h"
 
 namespace media {
 class VideoFrame;
 
 namespace cast {
 
 // This object is called external from the main cast thread and internally from
 // the video encoder thread.
 class VideoEncoderImpl : public VideoEncoder {
  public:
+  struct CodecDynamicConfig {
+    bool key_frame_requested;
+    uint32 latest_frame_id_to_reference;
+    int bit_rate;
+  };
+
   typedef base::Callback<void(scoped_ptr<transport::EncodedVideoFrame>,
                               const base::TimeTicks&)> FrameEncodedCallback;
 
   VideoEncoderImpl(scoped_refptr<CastEnvironment> cast_environment,
                    const VideoSenderConfig& video_config,
                    uint8 max_unacked_frames);
 
   virtual ~VideoEncoderImpl();
 
   // Called from the main cast thread. This function post the encode task to the
   // video encoder thread;
   // The video_frame must be valid until the closure callback is called.
   // The closure callback is called from the video encoder thread as soon as
   // the encoder is done with the frame; it does not mean that the encoded frame
   // has been sent out.
   // Once the encoded frame is ready the frame_encoded_callback is called.
   virtual bool EncodeVideoFrame(
       const scoped_refptr<media::VideoFrame>& video_frame,
       const base::TimeTicks& capture_time,
       const FrameEncodedCallback& frame_encoded_callback) OVERRIDE;
 
   // The following functions are called from the main cast thread.
   virtual void SetBitRate(int new_bit_rate) OVERRIDE;
   virtual void SkipNextFrame(bool skip_next_frame) OVERRIDE;
   virtual void GenerateKeyFrame() OVERRIDE;
   virtual void LatestFrameIdToReference(uint32 frame_id) OVERRIDE;
   virtual int NumberOfSkippedFrames() const OVERRIDE;
 
- protected:
-  struct CodecDynamicConfig {
-    bool key_frame_requested;
-    uint32 latest_frame_id_to_reference;
-    int bit_rate;
-  };
+ private:
 
-  // The actual encode, called from the video encoder thread.
-  void EncodeVideoFrameEncoderThread(
-      const scoped_refptr<media::VideoFrame>& video_frame,
-      const base::TimeTicks& capture_time,
-      const CodecDynamicConfig& dynamic_config,
-      const FrameEncodedCallback& frame_encoded_callback);
-
- private:
   const VideoSenderConfig video_config_;
   scoped_refptr<CastEnvironment> cast_environment_;
-  scoped_ptr<Vp8Encoder> vp8_encoder_;
   CodecDynamicConfig dynamic_config_;
   bool skip_next_frame_;
   int skip_count_;
 
+  // This member belongs to the video encoder thread. It must not be
+  // dereferenced on the main thread. We manage the lifetime of this member
+  // manually because it needs to be initialize, used and destroyed on the
+  // video encoder thread and video encoder thread can out-live the main thread.
+  scoped_ptr<Vp8Encoder> vp8_encoder_;
+
   DISALLOW_COPY_AND_ASSIGN(VideoEncoderImpl);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_VIDEO_SENDER_VIDEO_ENCODER_IMPL_H_