[WIP] Move media/capture to device/capture

media/capture/content/screen_capture_device_core.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_CAPTURE_CONTENT_SCREEN_CAPTURE_DEVICE_CORE_H_
-#define MEDIA_CAPTURE_CONTENT_SCREEN_CAPTURE_DEVICE_CORE_H_
-
-#include <memory>
-#include <string>
-
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "base/threading/thread_checker.h"
-#include "media/capture/capture_export.h"
-#include "media/capture/content/thread_safe_capture_oracle.h"
-#include "media/capture/video/video_capture_device.h"
-
-namespace tracked_objects {
-class Location;
-}  // namespace tracked_objects
-
-namespace media {
-
-struct VideoCaptureParams;
-
-class ThreadSafeCaptureOracle;
-
-// Keeps track of the video capture source frames and executes copying.
-class CAPTURE_EXPORT VideoCaptureMachine {
- public:
-  VideoCaptureMachine();
-  virtual ~VideoCaptureMachine();
-
-  // Starts capturing.
-  // |callback| is invoked with true if succeeded. Otherwise, with false.
-  virtual void Start(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
-                     const VideoCaptureParams& params,
-                     const base::Callback<void(bool)> callback) = 0;
-
-  // Stops capturing.
-  // |callback| is invoked after the capturing has stopped.
-  virtual void Stop(const base::Closure& callback) = 0;
-
-  // Returns true if the video capture is configured to monitor end-to-end
-  // system utilization, and alter frame sizes and/or frame rates to mitigate
-  // overloading or under-utilization.
-  virtual bool IsAutoThrottlingEnabled() const;
-
-  // Called by ScreenCaptureDeviceCore when it failed to satisfy a "refresh
-  // frame" request by attempting to resurrect the last video frame from the
-  // buffer pool (this is referred to as the "passive" refresh approach).  The
-  // failure can happen for a number of reasons (e.g., the oracle decided to
-  // change resolution, or consumers of the last video frame are not yet
-  // finished with it).
-  //
-  // The implementation of this method should consult the oracle, using the
-  // kActiveRefreshRequest event type, to decide whether to initiate a new frame
-  // capture, and then do so if the oracle agrees.
-  virtual void MaybeCaptureForRefresh() = 0;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(VideoCaptureMachine);
-};
-
-// The "meat" of a content video capturer.
-//
-// Separating this from the "shell classes" WebContentsVideoCaptureDevice and
-// DesktopCaptureDeviceAura allows safe destruction without needing to block any
-// threads, as well as code sharing.
-//
-// ScreenCaptureDeviceCore 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 CAPTURE_EXPORT ScreenCaptureDeviceCore
-    : public base::SupportsWeakPtr<ScreenCaptureDeviceCore> {
- public:
-  ScreenCaptureDeviceCore(std::unique_ptr<VideoCaptureMachine> capture_machine);
-  virtual ~ScreenCaptureDeviceCore();
-
-  // Asynchronous requests to change ScreenCaptureDeviceCore state.
-  void AllocateAndStart(const VideoCaptureParams& params,
-                        std::unique_ptr<VideoCaptureDevice::Client> client);
-  void RequestRefreshFrame();
-  void StopAndDeAllocate();
-
- private:
-  // Flag indicating current state.
-  enum State { kIdle, kCapturing, kError, kLastCaptureState };
-
-  void TransitionStateTo(State next_state);
-
-  // Called back 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(const tracked_objects::Location& from_here,
-             const std::string& reason);
-
-  // 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 device thread or UI thread.
-  // This value should never be dereferenced by this class.
-  std::unique_ptr<VideoCaptureMachine> capture_machine_;
-
-  // Our thread-safe capture oracle which serves as the gateway to the video
-  // capture pipeline. Besides the VideoCaptureDevice itself, it is the only
-  // component of the system with direct access to |client_|.
-  scoped_refptr<ThreadSafeCaptureOracle> oracle_proxy_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScreenCaptureDeviceCore);
-};
-
-}  // namespace media
-
-#endif  // MEDIA_CAPTURE_CONTENT_SCREEN_CAPTURE_DEVICE_CORE_H_