Modify the RenderThread to track the number of widgets...

chrome/renderer/mock_render_thread.h

Index: chrome/renderer/mock_render_thread.h
===================================================================
--- chrome/renderer/mock_render_thread.h	(revision 24223)
+++ chrome/renderer/mock_render_thread.h	(working copy)
@@ -41,11 +41,13 @@
   virtual bool Send(IPC::Message* msg);
 
   // Our mock thread doesn't do filtering.
-  virtual void AddFilter(IPC::ChannelProxy::MessageFilter* filter) {
-  }
-  virtual void RemoveFilter(IPC::ChannelProxy::MessageFilter* filter) {
-  }
+  virtual void AddFilter(IPC::ChannelProxy::MessageFilter* filter) { }
+  virtual void RemoveFilter(IPC::ChannelProxy::MessageFilter* filter) { }
 
+  // Our mock thread doesn't deal with hidden and restored tabs.
+  virtual void WidgetHidden() { }
+  virtual void WidgetRestored() { }
+
   //////////////////////////////////////////////////////////////////////////
   // The following functions are called by the test itself.