Force accelerated 2d canvas off for chrome ui

BUG=56455
TEST=start chrome with --enable-accelerated-2d-canvas, open bookmark manager, verify there is no GPU process

Review URL: http://codereview.chromium.org/3413027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@60206 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/tab_contents/tab_contents.cc b/chrome/browser/tab_contents/tab_contents.cc
index 5edfb32..2578b5a 100644
--- a/chrome/browser/tab_contents/tab_contents.cc
+++ b/chrome/browser/tab_contents/tab_contents.cc
@@ -2869,11 +2869,12 @@
   WebPreferences web_prefs =
       RenderViewHostDelegateHelper::GetWebkitPrefs(profile, is_dom_ui);
 
-  // Force accelerated compositing off for chrome: and chrome-extension:
-  // pages.
+  // Force accelerated compositing and 2d canvas off for chrome: and
+  // chrome-extension: pages.
   if (GetURL().SchemeIs(chrome::kChromeUIScheme) ||
       GetURL().SchemeIs(chrome::kExtensionScheme)) {
     web_prefs.accelerated_compositing_enabled = false;
+    web_prefs.accelerated_2d_canvas_enabled = false;
   }
 
 #if defined(OS_MACOSX)