Cleanup shared memory handling in DesktopCapturer interface.

webrtc/modules/desktop_capture/desktop_capturer.h

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_CAPTURER_H_
 #define WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_CAPTURER_H_
 
 #include <stddef.h>
 
+#include "webrtc/base/scoped_ptr.h"
 #include "webrtc/modules/desktop_capture/desktop_capture_types.h"
+#include "webrtc/modules/desktop_capture/shared_memory.h"
 
 namespace webrtc {
 
 class DesktopFrame;
 class DesktopRegion;
-class SharedMemory;
 
 // Abstract interface for screen and window capturers.
 class DesktopCapturer {
  public:
   // Interface that must be implemented by the DesktopCapturer consumers.
   class Callback {
    public:
-    // Creates a new shared memory buffer for a frame create by the capturer.
-    // Should return null shared memory is not used for captured frames (in that
-    // case the capturer will allocate memory on the heap).
-    virtual SharedMemory* CreateSharedMemory(size_t size) = 0;
+    // Deprecated.
+    // TODO(sergeyu): Remove this method once all references to it are removed
+    // from chromium.
+    virtual SharedMemory* CreateSharedMemory(size_t size) { return nullptr; }
 
     // Called after a frame has been captured. Handler must take ownership of
     // |frame|. If capture has failed for any reason |frame| is set to NULL
     // (e.g. the window has been closed).
     virtual void OnCaptureCompleted(DesktopFrame* frame) = 0;
 
    protected:
     virtual ~Callback() {}
   };
 
   virtual ~DesktopCapturer() {}
 
   // Called at the beginning of a capturing session. |callback| must remain
   // valid until capturer is destroyed.
   virtual void Start(Callback* callback) = 0;
 
+  // Sets SharedMemoryFactory that will be used to create buffers for the
+  // captured frames. The factory can be invoked on a thread other than the one
+  // where Capture() is called. It will be destroyed on the same thread. Shared
+  // memory is currently supported only by some DesktopCapturer implementations.
+  virtual void SetSharedMemoryFactory(
+      rtc::scoped_ptr<SharedMemoryFactory> shared_memory_factory) {}
+
   // Captures next frame. |region| specifies region of the capture target that
   // should be fresh in the resulting frame. The frame may also include fresh
   // data for areas outside |region|. In that case capturer will include these
   // areas in updated_region() of the frame. |region| is specified relative to
   // the top left corner of the capture target. Pending capture operations are
   // canceled when DesktopCapturer is deleted.
   virtual void Capture(const DesktopRegion& region) = 0;
 
   // Sets the window to be excluded from the captured image in the future
   // Capture calls. Used to exclude the screenshare notification window for
   // screen capturing.
   virtual void SetExcludedWindow(WindowId window) {}
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_CAPTURER_H_