Give prerendering RVH's RenderWidgetHostViews.

chrome/browser/prerender/prerender_contents.h

Index: chrome/browser/prerender/prerender_contents.h
===================================================================
--- chrome/browser/prerender/prerender_contents.h	(revision 82482)
+++ chrome/browser/prerender/prerender_contents.h	(working copy)
@@ -20,10 +20,11 @@
 #include "content/common/window_container_type.h"
 #include "webkit/glue/window_open_disposition.h"
 
+class RenderViewHost;
 class TabContents;
 struct FaviconURL;
+struct ViewHostMsg_FrameNavigate_Params;
 struct WebPreferences;
-struct ViewHostMsg_FrameNavigate_Params;
 
 namespace base {
 class ProcessMetrics;
@@ -66,7 +67,10 @@
 
   static Factory* CreateFactory();
 
-  virtual void StartPrerendering();
+  // |source_render_view_host| is the RenderViewHost that initiated
+  // prerendering.  It must be non-NULL and have its own view.  It is used
+  // solely to determine the window bounds while prerendering.
+  virtual void StartPrerendering(const RenderViewHost* source_render_view_host);
 
   // Verifies that the prerendering is not using too many resources, and kills
   // it if not.