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 98900)
+++ content/browser/tab_contents/tab_contents_delegate.h	(working copy)
@@ -338,6 +338,10 @@
                                  const string16& data,
                                  int intent_id);
 
+  // Invoked when the preferred size of the contents has been changed.
+  virtual void UpdatePreferredSize(TabContents* source,
+                                   const gfx::Size& pref_size);
+
  protected:
   virtual ~TabContentsDelegate();