Change snasphotting API to take in a bounds Rect

chrome/browser/ui/window_snapshot/window_snapshot.h

 // Copyright (c) 2011 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 CHROME_BROWSER_UI_WINDOW_SNAPSHOT_WINDOW_SNAPSHOT_H_
 #define CHROME_BROWSER_UI_WINDOW_SNAPSHOT_WINDOW_SNAPSHOT_H_
 #pragma once
 
 #include <vector>
 
 #include "ui/gfx/native_widget_types.h"
 
 namespace gfx {
   class Rect;
 }
 
 namespace browser {
 
-// Grabs a snapshot of the designated window and stores a PNG representation
-// into a byte vector. Returns the image bounds.
-gfx::Rect GrabWindowSnapshot(gfx::NativeWindow window,
-                             std::vector<unsigned char>* png_representation);
+// Grabs a snapshot of the rectangle area |snapshot_bounds| with respect to the
+// top left corner of the designated window and stores a PNG representation
+// into a byte vector. Returns true if the operation is successful.
+bool GrabWindowSnapshot(gfx::NativeWindow window,
+                        std::vector<unsigned char>* png_representation,
+                        const gfx::Rect& snapshot_bounds);
 
 }  // namespace browser
 
 #endif  // CHROME_BROWSER_UI_WINDOW_SNAPSHOT_WINDOW_SNAPSHOT_H_