[Cast] Refactor ExternalVideoEncoder for cleaner/simpler encapsulation.

media/cast/sender/external_video_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_EXTERNAL_VIDEO_ENCODER_H_
 #define MEDIA_CAST_SENDER_EXTERNAL_VIDEO_ENCODER_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/sender/video_encoder.h"
 #include "media/video/video_encode_accelerator.h"
-
-namespace media {
-class VideoFrame;
-}
+#include "ui/gfx/geometry/size.h"
 
 namespace media {
 namespace cast {
 
-class LocalVideoEncodeAcceleratorClient;
-
-// This object is called external from the main cast thread and internally from
-// the video encoder thread.
+// Cast MAIN thread proxy to the internal media::VideoEncodeAccelerator
+// implementation running on a separate thread.  Encodes media::VideoFrames and
+// emits media::cast::EncodedFrames.
 class ExternalVideoEncoder : public VideoEncoder {
  public:
   ExternalVideoEncoder(
-      scoped_refptr<CastEnvironment> cast_environment,
+      const scoped_refptr<CastEnvironment>& cast_environment,
       const VideoSenderConfig& video_config,
+      const gfx::Size& frame_size,
       const CastInitializationCallback& initialization_cb,
       const CreateVideoEncodeAcceleratorCallback& create_vea_cb,
-      const CreateVideoEncodeMemoryCallback& create_video_encode_mem_cb);
+      const CreateVideoEncodeMemoryCallback& create_video_encode_memory_cb);
 
   ~ExternalVideoEncoder() override;
 
   // 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;
 
-  // Called when video_accelerator_client_ has finished creating the VEA and
-  // is ready for use.
+ private:
+  class VEAClientImpl;
+
+  // Method invoked by the CreateVideoEncodeAcceleratorCallback to construct a
+  // VEAClientImpl to own and interface with a new |vea|.  Upon return,
+  // |client_| holds a reference to the new VEAClientImpl.
   void OnCreateVideoEncodeAccelerator(
-      scoped_refptr<base::SingleThreadTaskRunner> encoder_task_runner);
+      const gfx::Size& frame_size,
+      VideoCodecProfile codec_profile,
+      int max_frame_rate,
+      const CastInitializationCallback& initialization_cb,
+      scoped_refptr<base::SingleThreadTaskRunner> encoder_task_runner,
+      scoped_ptr<media::VideoEncodeAccelerator> vea);
 
- protected:
-  // If |success| is true then encoder is initialized successfully.
-  // Otherwise encoder initialization failed.
-  void EncoderInitialized(bool success);
-  void EncoderError();
-
- private:
-  friend class LocalVideoEncodeAcceleratorClient;
-
-  VideoSenderConfig video_config_;
-  scoped_refptr<CastEnvironment> cast_environment_;
-
-  bool encoder_active_;
+  const scoped_refptr<CastEnvironment> cast_environment_;
+  const CreateVideoEncodeMemoryCallback create_video_encode_memory_cb_;
+  int bit_rate_;
   bool key_frame_requested_;
 
-  scoped_refptr<LocalVideoEncodeAcceleratorClient> video_accelerator_client_;
-  scoped_refptr<base::SingleThreadTaskRunner> encoder_task_runner_;
+  scoped_refptr<VEAClientImpl> client_;
 
-  CastInitializationCallback initialization_cb_;
-
-  // Weak pointer factory for posting back LocalVideoEncodeAcceleratorClient
-  // notifications to ExternalVideoEncoder.
+  // Provides a weak pointer for the OnCreateVideoEncoderAccelerator() callback.
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<ExternalVideoEncoder> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalVideoEncoder);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_SENDER_EXTERNAL_VIDEO_ENCODER_H_