[test fixlet] Add tests for the zoom icon in the location bar on GTK.

chrome/browser/ui/gtk/zoom_bubble_gtk.h

Index: chrome/browser/ui/gtk/zoom_bubble_gtk.h
diff --git a/chrome/browser/ui/gtk/zoom_bubble_gtk.h b/chrome/browser/ui/gtk/zoom_bubble_gtk.h
index a46c9f252f9bb278f4c838b289eb67af31a2d754..db8421055a2a8af861901ba5e381f050be7a5c69 100644
--- a/chrome/browser/ui/gtk/zoom_bubble_gtk.h
+++ b/chrome/browser/ui/gtk/zoom_bubble_gtk.h
@@ -23,6 +23,9 @@ class ZoomBubbleGtk {
   // Closes the zoom bubble.
   static void Close();
 
+  // Whether the zoom bubble is currently showing.
+  static bool IsShowing();
+
  private:
   ZoomBubbleGtk(GtkWidget* anchor, TabContents* tab_contents, bool auto_close);
   virtual ~ZoomBubbleGtk();
@@ -52,6 +55,12 @@ class ZoomBubbleGtk {
   CHROMEGTK_CALLBACK_1(ZoomBubbleGtk, gboolean, OnMouseLeave,
                        GdkEventCrossing*);
 
+  // Friend the tests so they can access the static bubble.
+  friend class ZoomBubbleGtkTest;
+
+  // Pointer to singleton object (NULL if no bubble is open).
+  static ZoomBubbleGtk* g_bubble;
+
   // Whether the currently displayed bubble will automatically close.
   bool auto_close_;