Give the main frame a RenderWidget.

chrome/browser/ui/browser.h

Index: chrome/browser/ui/browser.h
diff --git a/chrome/browser/ui/browser.h b/chrome/browser/ui/browser.h
index 56add135c3899cd979499b860705aa8b8b8e745a..3f61ea10ff5733082a87aa610add6cbbc4ce7dd9 100644
--- a/chrome/browser/ui/browser.h
+++ b/chrome/browser/ui/browser.h
@@ -584,8 +584,10 @@ class Browser : public TabStripModelObserver,
   void ShowRepostFormWarningDialog(content::WebContents* source) override;
   bool ShouldCreateWebContents(
       content::WebContents* web_contents,
-      int route_id,
-      int main_frame_route_id,
+      int32 route_id,
+      int32 main_frame_route_id,
+      int32 main_frame_widget_route_id,
+      int32 surface_id,
       WindowContainerType window_container_type,
       const std::string& frame_name,
       const GURL& target_url,
@@ -826,8 +828,10 @@ class Browser : public TabStripModelObserver,
   // Creates a BackgroundContents if appropriate; return true if one was
   // created.
   bool MaybeCreateBackgroundContents(
-      int route_id,
-      int main_frame_route_id,
+      int32 route_id,
+      int32 main_frame_route_id,
+      int32 main_frame_widget_route_id,
+      int32 surface_id,
       content::WebContents* opener_web_contents,
       const std::string& frame_name,
       const GURL& target_url,