Have ExtensionHost use TabContents instead of RenderViewHost. Try #3.

chrome/browser/extensions/extension_webkit_preferences.cc

Index: chrome/browser/extensions/extension_webkit_preferences.cc
diff --git a/chrome/browser/extensions/extension_webkit_preferences.cc b/chrome/browser/extensions/extension_webkit_preferences.cc
index 4be4be7faef99d5718840956ce3c9f279579feff..c598992d37dc3636b3fe1e175d2663122d5e9676 100644
--- a/chrome/browser/extensions/extension_webkit_preferences.cc
+++ b/chrome/browser/extensions/extension_webkit_preferences.cc
@@ -2,13 +2,16 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "webkit/glue/webpreferences.h"
+#include "chrome/browser/extensions/extension_webkit_preferences.h"
 
 #include "chrome/common/extensions/extension.h"
+#include "webkit/glue/webpreferences.h"
 
 namespace extension_webkit_preferences {
 
-void SetPreferences(WebPreferences* webkit_prefs, const Extension* extension) {
+void SetPreferences(const Extension* extension,
+                    content::ViewType render_view_type,
+                    WebPreferences* webkit_prefs) {
   if (extension && !extension->is_hosted_app()) {
     // Extensions are trusted so we override any user preferences for disabling
     // javascript or images.
@@ -21,6 +24,14 @@ void SetPreferences(WebPreferences* webkit_prefs, const Extension* extension) {
 
     // Enable privileged WebGL extensions.
     webkit_prefs->privileged_webgl_extensions_enabled = true;
+
+    // Disable anything that requires the GPU process for background pages.
+    // See http://crbug.com/64512 and http://crbug.com/64841.
+    if (render_view_type == chrome::VIEW_TYPE_EXTENSION_BACKGROUND_PAGE) {
+      webkit_prefs->experimental_webgl_enabled = false;
+      webkit_prefs->accelerated_compositing_enabled = false;
+      webkit_prefs->accelerated_2d_canvas_enabled = false;
+    }
   }
 }