Update Panel mininimize/restore button on strip and expansion state change.

chrome/browser/ui/panels/panel_browser_window_gtk.h

Index: chrome/browser/ui/panels/panel_browser_window_gtk.h
diff --git a/chrome/browser/ui/panels/panel_browser_window_gtk.h b/chrome/browser/ui/panels/panel_browser_window_gtk.h
index 25e8181056b61eb83c7dc691cd3f3ee96407514b..817c65d7f1216f4705c59c0ddd3421e837086fbd 100644
--- a/chrome/browser/ui/panels/panel_browser_window_gtk.h
+++ b/chrome/browser/ui/panels/panel_browser_window_gtk.h
@@ -111,9 +111,9 @@ class PanelBrowserWindowGtk : public BrowserWindowGtk,
       const gfx::Size& window_size) const OVERRIDE;
   virtual int TitleOnlyHeight() const OVERRIDE;
   virtual void EnsurePanelFullyVisible() OVERRIDE;
-  virtual void SetPanelAppIconVisibility(bool visible) OVERRIDE;
   virtual void SetPanelAlwaysOnTop(bool on_top) OVERRIDE;
   virtual void EnableResizeByMouse(bool enable) OVERRIDE;
+  virtual void UpdateMinimizeRestoreButtonVisibility() OVERRIDE;
 
  private:
   friend class NativePanelTestingGtk;