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content/browser/renderer_host/media/video_capture_device_impl.h

Index: content/browser/renderer_host/media/video_capture_device_impl.h
diff --git a/content/browser/renderer_host/media/video_capture_device_impl.h b/content/browser/renderer_host/media/video_capture_device_impl.h
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+// Copyright 2013 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_RENDERER_HOST_VIDEO_CAPTURE_DEVICE_IMPL_H_
+#define CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_DEVICE_IMPL_H_
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread.h"
+#include "base/threading/thread_checker.h"
+#include "content/browser/renderer_host/media/video_capture_oracle.h"
+#include "content/common/content_export.h"
+#include "media/video/capture/video_capture_device.h"
+
+namespace content {
+
+const int kMinFrameWidth = 2;
+const int kMinFrameHeight = 2;
+
+// Returns the nearest even integer closer to zero.
+template<typename IntType>
+IntType MakeEven(IntType x) {
+  return x & static_cast<IntType>(-2);
+}
+
+// TODO(nick): Remove this once frame subscription is supported on Aura and
+// Linux.
+#if (defined(OS_WIN) || defined(OS_MACOSX)) || defined(USE_AURA)
+const bool kAcceleratedSubscriberIsSupported = true;
+#else
+const bool kAcceleratedSubscriberIsSupported = false;
+#endif
+
+class VideoCaptureMachine;
+
+// Thread-safe, refcounted proxy to the VideoCaptureOracle.  This proxy wraps
+// the VideoCaptureOracle, which decides which frames to capture, and a
+// VideoCaptureDevice::Client, which allocates and receives the captured
+// frames, in a lock to synchronize state between the two.
+class ThreadSafeCaptureOracle
+    : public base::RefCountedThreadSafe<ThreadSafeCaptureOracle> {
+ public:
+  ThreadSafeCaptureOracle(scoped_ptr<media::VideoCaptureDevice::Client> client,
+                          scoped_ptr<VideoCaptureOracle> oracle,
+                          const gfx::Size& capture_size,
+                          int frame_rate);
+
+  // Called when a captured frame is available or an error has occurred.
+  // If |success| is true then the frame provided is valid and |timestamp|
+  // indicates when the frame was painted.
+  // If |success| is false, both the frame provided and |timestamp| are invalid.
+  typedef base::Callback<void(base::Time timestamp, bool success)>
+      CaptureFrameCallback;
+
+  bool ObserveEventAndDecideCapture(VideoCaptureOracle::Event event,
+                                    base::Time event_time,
+                                    scoped_refptr<media::VideoFrame>* storage,
+                                    CaptureFrameCallback* callback);
+
+  base::TimeDelta capture_period() const {
+    return oracle_->capture_period();
+  }
+
+  // Stop new captures from happening (but doesn't forget the client).
+  void Stop();
+
+  // Signal an error to the client.
+  void ReportError();
+
+ private:
+  friend class base::RefCountedThreadSafe<ThreadSafeCaptureOracle>;
+  virtual ~ThreadSafeCaptureOracle();
+
+  // Callback invoked on completion of all captures.
+  void DidCaptureFrame(
+      scoped_refptr<media::VideoCaptureDevice::Client::Buffer> buffer,
+      int frame_number,
+      base::Time timestamp,
+      bool success);
+  // Protects everything below it.
+  base::Lock lock_;
+
+  // Recipient of our capture activity.
+  scoped_ptr<media::VideoCaptureDevice::Client> client_;
+
+  // Makes the decision to capture a frame.
+  const scoped_ptr<VideoCaptureOracle> oracle_;
+
+  // The current capturing resolution and frame rate.
+  const gfx::Size capture_size_;
+  const int frame_rate_;
+};
+
+// Keeps track of the video capture source frames and executes copying on the
+// UI BrowserThread.
+class VideoCaptureMachine {
+ public:
+  VideoCaptureMachine() : started_(false) {}
+  virtual ~VideoCaptureMachine() {}
+
+  // This should only be checked on the UI thread.
+  bool started() const { return started_; }
+
+  // Starts capturing. Returns true if succeeded.
+  // Must be run on the UI BrowserThread.
+  virtual bool Start(
+      const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy) = 0;
+
+  // Stops capturing. Must be run on the UI BrowserThread.
+  virtual void Stop() = 0;
+
+ protected:
+  bool started_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(VideoCaptureMachine);
+};
+
+// The "meat" of the video capture implementation.
+//
+// Separating this from the "shell classes" WebContentsVideoCaptureDevice and
+// BrowserCompositorCaptureDevice allows safe destruction without needing to
+// block any threads (e.g., the IO BrowserThread), as well as code sharing.
+//
+// VideoCaptureDeviceImpl manages a simple state machine and the pipeline (see
+// notes at top of this file).  It times the start of successive
+// captures and facilitates the processing of each through the stages of the
+// pipeline.
+class CONTENT_EXPORT VideoCaptureDeviceImpl
+    : public base::SupportsWeakPtr<VideoCaptureDeviceImpl> {
+ public:
+  VideoCaptureDeviceImpl(scoped_ptr<VideoCaptureMachine> capture_machine);
+  virtual ~VideoCaptureDeviceImpl();
+
+  // Asynchronous requests to change VideoCaptureDeviceImpl state.
+  void AllocateAndStart(const media::VideoCaptureParams& params,
+                        scoped_ptr<media::VideoCaptureDevice::Client> client);
+  void StopAndDeAllocate();
+
+ private:
+  // Flag indicating current state.
+  enum State {
+    kIdle,
+    kCapturing,
+    kError
+  };
+
+  void TransitionStateTo(State next_state);
+
+  // Called on the IO thread in response to StartCaptureMachine().
+  // |success| is true if capture machine succeeded to start.
+  void CaptureStarted(bool success);
+
+  // Stops capturing and notifies client_ of an error state.
+  void Error();
+
+  // Tracks that all activity occurs on the media stream manager's thread.
+  base::ThreadChecker thread_checker_;
+
+  // Current lifecycle state.
+  State state_;
+
+  // Tracks the CaptureMachine that's doing work on our behalf on the UI thread.
+  // This value should never be dereferenced by this class, other than to
+  // create and destroy it on the UI thread.
+  scoped_ptr<VideoCaptureMachine> capture_machine_;
+
+  // Our thread-safe capture oracle which serves as the gateway to the video
+  // capture pipeline. Besides the WCVCD itself, it is the only component of the
+  // system with direct access to |client_|.
+  scoped_refptr<ThreadSafeCaptureOracle> oracle_proxy_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoCaptureDeviceImpl);
+};
+
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_DEVICE_IMPL_H_