Make panel adjust bounds per preferred size change notification on Windows.

content/browser/tab_contents/tab_contents_delegate.h

Index: content/browser/tab_contents/tab_contents_delegate.h
===================================================================
--- content/browser/tab_contents/tab_contents_delegate.h	(revision 95921)
+++ content/browser/tab_contents/tab_contents_delegate.h	(working copy)
@@ -298,6 +298,9 @@
   // and displays nothing.
   virtual content::JavaScriptDialogCreator* GetJavaScriptDialogCreator();
 
+  // Invoked when the preferred size of the contents has been changed.
+  virtual void UpdatePreferredSize(const gfx::Size& pref_size);
+
  protected:
   virtual ~TabContentsDelegate();