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

chrome/browser/gtk/browser_toolbar_gtk.h

Index: chrome/browser/gtk/browser_toolbar_gtk.h
===================================================================
--- chrome/browser/gtk/browser_toolbar_gtk.h	(revision 18718)
+++ chrome/browser/gtk/browser_toolbar_gtk.h	(working copy)
@@ -109,6 +109,10 @@
   // Gtk callback for the "clicked" signal.
   static void OnButtonClick(GtkWidget* button, BrowserToolbarGtk* toolbar);
 
+  // Gtk callback for the "button-release-event" signal.
+  static gboolean OnButtonRelease(GtkWidget* button, GdkEventButton* event,
+                                  BrowserToolbarGtk* toolbar);
+
   // Gtk callback to intercept mouse clicks to the menu buttons.
   static gboolean OnMenuButtonPressEvent(GtkWidget* button,
                                          GdkEventButton* event,
@@ -151,6 +155,9 @@
   // Controls whether or not a home button should be shown on the toolbar.
   BooleanPrefMember show_home_button_;
 
+  // The event state the last time we observed a button release event.
+  int last_release_event_flags_;
+
   DISALLOW_COPY_AND_ASSIGN(BrowserToolbarGtk);
 };