Use bounds instead of size for prerender requests

chrome/browser/ui/web_contents_sizer.h

 // Copyright 2014 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_WEB_CONTENTS_SIZER_H_
 #define CHROME_BROWSER_UI_WEB_CONTENTS_SIZER_H_
 
 namespace content {
 class WebContents;
 }
 
 namespace gfx {
-class Size;
+class Rect;
 }
 
-// A platform-agnostic function to resize a WebContents. The top-left corner of
-// the WebContents does not move during the resizing.
+// A platform-agnostic function to resize a WebContents.
 void ResizeWebContents(content::WebContents* web_contents,
-                       const gfx::Size& size);
+                       const gfx::Rect& bounds);
 
 #endif  // CHROME_BROWSER_UI_WEB_CONTENTS_SIZER_H_