Screen Video Capture: Implement suspend optimization.

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>
 
@@ skipping 19 matching lines @@
  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;
 
+  // Suspend/Resume frame delivery. Implementations of these are optional.
+  virtual void Suspend() {}
+  virtual void Resume() {}
+
   // 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
@@ skipping 25 matching lines @@
 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 Suspend();
+  void Resume();
   void StopAndDeAllocate();
 
  private:
   // Flag indicating current state.
-  enum State { kIdle, kCapturing, kError, kLastCaptureState };
+  enum State { kIdle, kCapturing, kSuspended, 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);
@@ skipping 13 matching lines @@
   // 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_