Fix typo in setting event masks.

chrome/browser/gtk/tabs/tab_gtk.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/gtk/tabs/tab_gtk.h"
 
 #include <gdk/gdkkeysyms.h>
 
 #include "app/gtk_dnd_util.h"
 #include "app/menus/accelerator_gtk.h"
@@ skipping 134 matching lines @@
   g_signal_connect(event_box_, "button-press-event",
                    G_CALLBACK(OnButtonPressEventThunk), this);
   g_signal_connect(event_box_, "button-release-event",
                    G_CALLBACK(OnButtonReleaseEventThunk), this);
   g_signal_connect(event_box_, "enter-notify-event",
                    G_CALLBACK(OnEnterNotifyEventThunk), this);
   g_signal_connect(event_box_, "leave-notify-event",
                    G_CALLBACK(OnLeaveNotifyEventThunk), this);
   gtk_widget_add_events(event_box_,
         GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
-        GDK_LEAVE_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
+        GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
   gtk_container_add(GTK_CONTAINER(event_box_), TabRendererGtk::widget());
   gtk_widget_show_all(event_box_);
 }
 
 TabGtk::~TabGtk() {
   if (drag_widget_) {
     // Shadow the drag grab so the grab terminates. We could do this using any
     // widget, |drag_widget_| is just convenient.
     gtk_grab_add(drag_widget_);
     gtk_grab_remove(drag_widget_);
@@ skipping 233 matching lines @@
     gdk_event_free(last_mouse_down_);
     last_mouse_down_ = NULL;
   }
 
   // Notify the drag helper that we're done with any potential drag operations.
   // Clean up the drag helper, which is re-created on the next mouse press.
   delegate_->EndDrag(canceled);
 
   observer_.reset();
 }