Adapt encoder behavior to target bitrate

remoting/protocol/webrtc_video_encoder.h

 // Copyright 2016 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 REMOTING_PROTOCOL_WEBRTC_VIDEO_ENCODER_H_
 #define REMOTING_PROTOCOL_WEBRTC_VIDEO_ENCODER_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/synchronization/lock.h"
 #include "remoting/proto/video.pb.h"
 #include "third_party/webrtc/media/engine/webrtcvideoencoderfactory.h"
 #include "third_party/webrtc/modules/video_coding/include/video_codec_interface.h"
 
 namespace remoting {
 
+using TargetBitrateCallback = base::Callback<void(uint32_t)>;
+
 // This is the interface between the WebRtc engine and the external encoder
 // provided by remoting. WebRtc provides feedback on network bandwidth, latency
 // & RTT and in turn remoting passes encoded frames as they get encoded
 // through the capture pipeline.
 class WebRtcVideoEncoder : public webrtc::VideoEncoder {
  public:
   enum State { kUninitialized = 0, kInitialized };
   explicit WebRtcVideoEncoder(webrtc::VideoCodecType codec);
   ~WebRtcVideoEncoder() override;
 
   // webrtc::VideoEncoder overrides
   int32_t InitEncode(const webrtc::VideoCodec* codec_settings,
                      int32_t number_of_cores,
                      size_t max_payload_size) override;
   int32_t RegisterEncodeCompleteCallback(
       webrtc::EncodedImageCallback* callback) override;
   int32_t Release() override;
   int32_t Encode(const webrtc::VideoFrame& frame,
                  const webrtc::CodecSpecificInfo* codec_specific_info,
                  const std::vector<webrtc::FrameType>* frame_types) override;
   int32_t SetChannelParameters(uint32_t packet_loss, int64_t rtt) override;
   int32_t SetRates(uint32_t bitrate, uint32_t framerate) override;
 
   int SendEncodedFrame(int64_t capture_timestamp_ms,
                        std::unique_ptr<VideoPacket> pkt);
   void SetKeyFrameRequestCallback(const base::Closure& key_frame_request);
+  void SetTargetBitrateCallback(const TargetBitrateCallback& target_bitrate_cb);
 
  private:
-  // Protects |encoded_callback_|, |key_frame_request_| and |state_|.
+  // Protects |encoded_callback_|, |key_frame_request_|,
+  // |target_bitrate_cb_| and |state_|.
   base::Lock lock_;
   State state_;
   webrtc::EncodedImageCallback* encoded_callback_;
 
   base::Closure key_frame_request_;
+  TargetBitrateCallback target_bitrate_cb_;
   webrtc::VideoCodecType video_codec_type_;
-  uint32_t target_bitrate_;
 };
 
 // This is the external encoder factory implementation that is passed to
 // WebRTC at the time of creation of peer connection. The external encoder
 // factory primarily manages creation and destruction of encoder.
 class WebRtcVideoEncoderFactory : public cricket::WebRtcVideoEncoderFactory {
  public:
   WebRtcVideoEncoderFactory();
   ~WebRtcVideoEncoderFactory() override;
 
   webrtc::VideoEncoder* CreateVideoEncoder(
       webrtc::VideoCodecType type) override;
   const std::vector<cricket::WebRtcVideoEncoderFactory::VideoCodec>& codecs()
       const override;
 
   // Returns true to directly provide encoded frames to webrtc
   bool EncoderTypeHasInternalSource(webrtc::VideoCodecType type) const override;
   void DestroyVideoEncoder(webrtc::VideoEncoder* encoder) override;
 
   int SendEncodedFrame(int64_t capture_timestamp_ms,
                        std::unique_ptr<VideoPacket> pkt);
 
   void SetKeyFrameRequestCallback(const base::Closure& key_frame_request);
+  void SetTargetBitrateCallback(const TargetBitrateCallback& target_bitrate_cb);
 
  private:
-  // Protects |key_frame_request_|.
+  // Protects |key_frame_request_| and |target_bitrate_cb_|.
   base::Lock lock_;
   base::Closure key_frame_request_;
+  TargetBitrateCallback target_bitrate_cb_;
   std::vector<cricket::WebRtcVideoEncoderFactory::VideoCodec> codecs_;
   std::vector<std::unique_ptr<WebRtcVideoEncoder>> encoders_;
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_WEBRTC_VIDEO_ENCODER_H_