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

chrome/browser/ui/browser_window.h

Index: chrome/browser/ui/browser_window.h
===================================================================
--- chrome/browser/ui/browser_window.h	(revision 95921)
+++ chrome/browser/ui/browser_window.h	(working copy)
@@ -33,6 +33,7 @@
 
 namespace gfx {
 class Rect;
+class Size;
 }
 
 class Extension;
@@ -341,6 +342,10 @@
   virtual void ShowKeyboardOverlay(gfx::NativeWindow owning_window) = 0;
 #endif
 
+  // Invoked when the preferred size of the contents has been changed. We might
+  // choose to update the window size to accomodate this change.
+  virtual void UpdatePreferredSize(const gfx::Size& pref_size) {}
+
   // Construct a BrowserWindow implementation for the specified |browser|.
   static BrowserWindow* CreateBrowserWindow(Browser* browser);