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

webrtc/modules/desktop_capture/shared_desktop_frame.h

Index: webrtc/modules/desktop_capture/shared_desktop_frame.h
diff --git a/webrtc/modules/desktop_capture/shared_desktop_frame.h b/webrtc/modules/desktop_capture/shared_desktop_frame.h
index 4f6a2bb7c693ea9c265d7c03c2a3b13ba4210cb1..49ff189cb4ab96f93ac80caf1aaf51ef214cce12 100644
--- a/webrtc/modules/desktop_capture/shared_desktop_frame.h
+++ b/webrtc/modules/desktop_capture/shared_desktop_frame.h
@@ -23,13 +23,18 @@ class SharedDesktopFrame : public DesktopFrame {
  public:
   virtual ~SharedDesktopFrame();
 
+  static std::unique_ptr<SharedDesktopFrame> Wrap(
+      std::unique_ptr<DesktopFrame> desktop_frame);
+
+  // Deprecated.
+  // TODO(sergeyu): remove this method.
   static SharedDesktopFrame* Wrap(DesktopFrame* desktop_frame);
 
   // Returns the underlying instance of DesktopFrame.
   DesktopFrame* GetUnderlyingFrame();
 
   // Creates a clone of this object.
-  SharedDesktopFrame* Share();
+  std::unique_ptr<SharedDesktopFrame> Share();
 
   // Checks if the frame is currently shared. If it returns false it's
   // guaranteed that there are no clones of the object.