[WebRTC] Add ScreenCapturerDifferWrapper to share Differ across ScreenCapturers

webrtc/modules/desktop_capture/desktop_geometry.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.
  */
 
@@ skipping 110 matching lines @@
   // Returns true if |rect| lies within the boundaries of this rectangle.
   bool ContainsRect(const DesktopRect& rect) const;
 
   // Finds intersection with |rect|.
   void IntersectWith(const DesktopRect& rect);
 
   // Adds (dx, dy) to the position of the rectangle.
   void Translate(int32_t dx, int32_t dy);
   void Translate(DesktopVector d) { Translate(d.x(), d.y()); };
 
+  // Enlarges current DesktopRect by subtracting |left_offset| and |top_offset|
+  // from |left_| and |top_|, and adding |right_offset| and |bottom_offset| to
+  // |right_| and |bottom_|. This function does not normalize the result, so
+  // |left_| and |top_| may be less than zero or larger than |right_| and
+  // |bottom_|.
+  void Extend(int32_t left_offset,
+              int32_t top_offset,
+              int32_t right_offset,
+              int32_t bottom_offset);
+
  private:
   DesktopRect(int32_t left, int32_t top, int32_t right, int32_t bottom)
       : left_(left), top_(top), right_(right), bottom_(bottom) {
   }
 
   int32_t left_;
   int32_t top_;
   int32_t right_;
   int32_t bottom_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_GEOMETRY_H_