Use std::unique_ptr<> to pass frame ownership in DesktopCapturer impls.

webrtc/modules/desktop_capture/cropping_window_capturer.h

 /*
  *  Copyright (c) 2014 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.
  */
 
@@ skipping 24 matching lines @@
   void Capture(const DesktopRegion& region) override;
   void SetExcludedWindow(WindowId window) override;
 
   // WindowCapturer implementation.
   bool GetWindowList(WindowList* windows) override;
   bool SelectWindow(WindowId id) override;
   bool BringSelectedWindowToFront() override;
 
   // DesktopCapturer::Callback implementation, passed to |screen_capturer_| to
   // intercept the capture result.
-  void OnCaptureCompleted(DesktopFrame* frame) override;
+  void OnCaptureCompleted(std::unique_ptr<DesktopFrame> frame) override;
 
  protected:
   explicit CroppingWindowCapturer(const DesktopCaptureOptions& options);
 
   // The platform implementation should override these methods.
 
   // Returns true if it is OK to capture the whole screen and crop to the
   // selected window, i.e. the selected window is opaque, rectangular, and not
   // occluded.
   virtual bool ShouldUseScreenCapturer() = 0;
@@ skipping 11 matching lines @@
   std::unique_ptr<WindowCapturer> window_capturer_;
   std::unique_ptr<ScreenCapturer> screen_capturer_;
   WindowId selected_window_;
   WindowId excluded_window_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_CROPPING_WINDOW_CAPTURER_H_