Add WebrtcVideoEncoder interface

remoting/codec/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_CODEC_WEBRTC_VIDEO_ENCODER_H_
+#define REMOTING_CODEC_WEBRTC_VIDEO_ENCODER_H_
+
+#include <stdint.h>
+
+#include <memory>
+
+#include "base/time/time.h"
+#include "third_party/webrtc/modules/desktop_capture/desktop_geometry.h"
+
+namespace webrtc {
+class DesktopFrame;
+}  // namespace webrtc
+
+namespace remoting {
+
+// A class to perform the task of encoding a continuous stream of images. The
+// interface is asynchronous to enable maximum throughput.
+class WebrtcVideoEncoder {
+ public:
+  struct FrameParams {
+    int bitrate_kbps = -1;
+    base::TimeDelta duration;
+    bool clear_active_map = false;

[Irfan, 2016/09/12 22:55:30]

It seems some of these are not used anywhere ? Can we add them when we need ?

[Sergey Ulanov, 2016/09/12 23:05:23]

Yes. Moved these fields to the follow-up CL where I need these fields:
https://codereview.chromium.org/2335923002/

+    bool key_frame = false;
+    int vpx_min_quantizer = -1;
+    int vpx_max_quantizer = -1;
+  };
+
+  struct EncodedFrame {
+    webrtc::DesktopSize size;
+    std::string data;
+    bool key_frame;
+    int quantizer;
+  };
+
+  virtual ~WebrtcVideoEncoder() {}
+
+  // Encode an image stored in |frame|. If |frame.updated_region()| is empty
+  // then the encoder may return a packet (e.g. to top-off previously-encoded
+  // portions of the frame to higher quality) or return nullptr to indicate that
+  // there is no work to do.
+  virtual std::unique_ptr<EncodedFrame> Encode(
+      const webrtc::DesktopFrame& frame,
+      const FrameParams& param) = 0;
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_CODEC_WEBRTC_VIDEO_ENCODER_H_