Make the gtk download shelf autoclose on mouse out.

chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc

 // Copyright (c) 2011 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/ui/gtk/tabs/tab_strip_gtk.h"
 
 #include <algorithm>
 
 #include "base/i18n/rtl.h"
 #include "base/string_util.h"
@@ skipping 1210 matching lines @@
   switch (event->type) {
     case GDK_MOTION_NOTIFY:
     case GDK_LEAVE_NOTIFY:
       HandleGlobalMouseMoveEvent();
       break;
     default:
       break;
   }
 }
 
+///////////////////////////////////////////////////////////////////////////////
+// TabStripGtk, NotificationObserver implementation:
+
 void TabStripGtk::Observe(NotificationType type,
                           const NotificationSource& source,
                           const NotificationDetails& details) {
   if (type == NotificationType::BROWSER_THEME_CHANGED) {
     TabRendererGtk::SetSelectedTitleColor(theme_provider_->GetColor(
         BrowserThemeProvider::COLOR_TAB_TEXT));
     TabRendererGtk::SetUnselectedTitleColor(theme_provider_->GetColor(
         BrowserThemeProvider::COLOR_BACKGROUND_TAB_TEXT));
   }
 }
@@ skipping 813 matching lines @@
 
   // Let the middle mouse button initiate clicks as well.
   gtk_util::SetButtonTriggersNavigation(button->widget());
   g_signal_connect(button->widget(), "clicked",
                    G_CALLBACK(OnNewTabClickedThunk), this);
   GTK_WIDGET_UNSET_FLAGS(button->widget(), GTK_CAN_FOCUS);
   gtk_fixed_put(GTK_FIXED(tabstrip_.get()), button->widget(), 0, 0);
 
   return button;
 }