Mojo Video Capture service in media/capture

media/capture/service/video_capture_device_client_impl.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 CONTENT_BROWSER_VIDEO_CAPTURE_VIDEO_CAPTURE_ADAPTER_H_
+#define CONTENT_BROWSER_VIDEO_CAPTURE_VIDEO_CAPTURE_ADAPTER_H_
+
+#include <string>
+
+#include "base/callback_forward.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "media/base/video_capture_types.h"
+#include "media/base/video_types.h"
+#include "media/capture/video/video_capture_device.h"
+
+namespace base {
+class TimeTicks;
+}
+
+namespace gfx {
+class Size;
+}
+
+namespace media {
+class VideoFrame;
+}
+
+namespace media {
+
+class MojoVideoFrame;
+
+// Device Client implementation. We are owned by a VideoCaptureDevice that calls
+// with captured data (usually via OnIncomingCapturedData()) that gets converted
+// into a VideoFrame and sent to our Delegate.
+// This class uses an internal VideoFramePool, a simple pool where allocated
+// VideoFrames have a SharedMemory inside. The interface-defined Buffer is a
+// thin wrapper around those.
+// This class lives inside whichever thread the VideoCaptureDevice lives. It
+// sends data back to its unique Delegate in that very thread.
+class VideoCaptureDeviceClientImpl : public media::VideoCaptureDevice::Client {

[perkj_chrome, 2016/03/03 13:12:42]

So this class is more or less the same as the existing VideoCaptureDeviceClient?
Is it possible to show only the diff somehow? git cl upload --similarity=...

[mcasas, 2016/03/03 18:41:15]

Too many things change:
- the current one has a VideoFramePool, whereas VCD relies on
 VCController owning it (and VCD using it)
- and because of that, there is a load of 
media::VideoCaptureDevice::Client::Buffer being passed
around that IMHO makes it very hard to reason as to what
is happening.

The current implementation is simplified.

+ public:
+  class Delegate {
+   public:
+    virtual ~Delegate() {}
+
+    // Called when a new |frame| is available, on Device Thread.
+    virtual void OnFrame(const scoped_refptr<MojoVideoFrame>& frame,
+                         const base::TimeTicks& timestamp) = 0;
+
+    // Called when there has been a fatal error which invalidates capture.
+    virtual void OnError(const std::string& reason) = 0;
+  };
+
+  // The Delegate implementation needs to be thread-safe. More specifically,
+  // each Delegate method should be safe to call on the same arbitrary thread.
+  // |delegate| is not owned and must outlive |this|.
+  explicit VideoCaptureDeviceClientImpl(Delegate* delegate);
+
+  ~VideoCaptureDeviceClientImpl() override;
+
+ private:
+  friend class VideoCaptureDeviceClientImplTest;
+  class VideoFramePool;
+
+  // media::VideoCaptureDevice::Client:
+  void OnIncomingCapturedData(const uint8_t* data,
+                              int length,
+                              const media::VideoCaptureFormat& frame_format,
+                              int clockwise_rotation,
+                              const base::TimeTicks& timestamp) override;
+  scoped_ptr<Buffer> ReserveOutputBuffer(
+      const gfx::Size& dimensions,
+      media::VideoPixelFormat pixel_format,
+      media::VideoPixelStorage pixel_storage) override;
+  void OnIncomingCapturedBuffer(scoped_ptr<Buffer> buffer,
+                                const media::VideoCaptureFormat& frame_format,
+                                const base::TimeTicks& timestamp) override;
+  void OnIncomingCapturedVideoFrame(
+      scoped_ptr<Buffer> buffer,
+      const scoped_refptr<media::VideoFrame>& frame,
+      const base::TimeTicks& timestamp) override;
+  void OnError(const tracked_objects::Location& from_here,
+               const std::string& reason) override;
+  double GetBufferPoolUtilization() const override;
+
+  // The |delegate_| to where we send the capture-converted VideoFrames.
+  Delegate* const delegate_;
+
+  // The underlying multithreaded MojoVideoFrame pool.
+  const scoped_refptr<VideoFramePool> video_frame_pool_;
+
+  // This class is single threaded except construction.
+  base::ThreadChecker thread_checker_;
+
+  base::WeakPtrFactory<VideoCaptureDeviceClientImpl> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoCaptureDeviceClientImpl);
+};
+
+}  // namespace media
+
+#endif  // CONTENT_BROWSER_VIDEO_CAPTURE_VIDEO_CAPTURE_ADAPTER_H_