Implement window open disposition for (some) navigation buttons....

chrome/browser/gtk/back_forward_button_gtk.h

Index: chrome/browser/gtk/back_forward_button_gtk.h
===================================================================
--- chrome/browser/gtk/back_forward_button_gtk.h	(revision 18718)
+++ chrome/browser/gtk/back_forward_button_gtk.h	(working copy)
@@ -36,6 +36,10 @@
                                 GdkEventButton* event,
                                 BackForwardButtonGtk* toolbar);
 
+  static gboolean OnButtonRelease(GtkWidget* button,
+                                  GdkEventButton* event,
+                                  BackForwardButtonGtk* toolbar);
+
   // If there is a timer to show the dropdown menu, and the mouse has moved
   // sufficiently down the screen, cancel the timer and immediately show the
   // menu.
@@ -57,6 +61,9 @@
   // Whether this button is a forward button.
   bool is_forward_;
 
+  // The event state from the last button release.
+  int last_release_event_flags_;
+
   // The dropdown menu delegate.
   scoped_ptr<BackForwardMenuModelGtk> menu_model_;