Add a command line switch to control accelerated 2d canvas

chrome/common/render_messages.h

Index: chrome/common/render_messages.h
diff --git a/chrome/common/render_messages.h b/chrome/common/render_messages.h
index 50b18c0d005d4e69a21a354bb4e1f1b5d9d04cef..1eab2cba850f810f10b33255b89ea3c19a00e015 100644
--- a/chrome/common/render_messages.h
+++ b/chrome/common/render_messages.h
@@ -2049,6 +2049,7 @@ struct ParamTraits<WebPreferences> {
     WriteParam(m, p.experimental_webgl_enabled);
     WriteParam(m, p.show_composited_layer_borders);
     WriteParam(m, p.accelerated_compositing_enabled);
+    WriteParam(m, p.accelerated_2d_canvas_enabled);
     WriteParam(m, p.memory_info_enabled);
   }
   static bool Read(const Message* m, void** iter, param_type* p) {
@@ -2094,6 +2095,7 @@ struct ParamTraits<WebPreferences> {
         ReadParam(m, iter, &p->experimental_webgl_enabled) &&
         ReadParam(m, iter, &p->show_composited_layer_borders) &&
         ReadParam(m, iter, &p->accelerated_compositing_enabled) &&
+        ReadParam(m, iter, &p->accelerated_2d_canvas_enabled) &&
         ReadParam(m, iter, &p->memory_info_enabled);
   }
   static void Log(const param_type& p, std::wstring* l) {