Automatic resolution throttling for screen capture pipeline.

media/capture/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_SCREEN_CAPTURE_DEVICE_CORE_H_
 #define MEDIA_CAPTURE_SCREEN_CAPTURE_DEVICE_CORE_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/media_export.h"
 #include "media/capture/thread_safe_capture_oracle.h"
 #include "media/video/capture/video_capture_device.h"
 
 namespace media {
 
 struct VideoCaptureParams;
 
 class ThreadSafeCaptureOracle;
 
 // Keeps track of the video capture source frames and executes copying.
-class VideoCaptureMachine {
+class MEDIA_EXPORT VideoCaptureMachine {
  public:
-  VideoCaptureMachine() {}
-  virtual ~VideoCaptureMachine() {}
+  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;
+
  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.
 //
@@ skipping 46 matching lines @@
   // component of the system with direct access to |client_|.
   scoped_refptr<ThreadSafeCaptureOracle> oracle_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenCaptureDeviceCore);
 };
 
 
 }  // namespace media
 
 #endif  // MEDIA_CAPTURE_SCREEN_CAPTURE_DEVICE_CORE_H_