Add support for getting the 256x256 app icon on Windows.

chrome/browser/app_icon_win.h

Index: chrome/browser/app_icon_win.h
===================================================================
--- chrome/browser/app_icon_win.h	(revision 176351)
+++ chrome/browser/app_icon_win.h	(working copy)
@@ -7,11 +7,15 @@
 
 #include <windows.h>
 
+#include "base/memory/scoped_ptr.h"
+
+class SkBitmap;
+
 HICON GetAppIcon();
 
 // Retrieve the application icon for the given size. Note that if you specify a
 // size other than what is contained in chrome.dll (16x16, 32x32, 48x48), this
-// might return a handle to a poorly resized icon.
-HICON GetAppIconForSize(int size);
+// might return a poorly resized icon.
+scoped_ptr<SkBitmap> GetAppIconForSize(int size);
 
 #endif  // CHROME_BROWSER_APP_ICON_WIN_H_