browser: Start moving application_lifetime.h functions into chrome namespace.

chrome/browser/lifetime/application_lifetime_gtk.cc

 // Copyright (c) 2012 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/lifetime/application_lifetime.h"
 
 #include <gtk/gtk.h>
 
-namespace browser {
+namespace chrome {
 
 void HandleAppExitingForPlatform() {
   // Close non-browser windows.
   GList* window_list = gtk_window_list_toplevels();
   g_list_foreach(window_list, (GFunc)g_object_ref, NULL);
   for (GList* i = window_list; i != NULL; i = g_list_next(i)) {
     GtkWindow* window = GTK_WINDOW(i->data);
     // We filter by visible widgets because there are toplevel windows that if
     // we try to destroy, we crash.  For example, trying to destroy the tooltip
     // window or the toplevel associated with drop down windows crashes.
     // We further filter to only close dialogs, as blindly closing all windows
     // causes problems with things like status icons.
     if (gtk_widget_get_visible(GTK_WIDGET(window)) &&
         (GTK_IS_DIALOG(GTK_WIDGET(window))))
       gtk_widget_destroy(GTK_WIDGET(window));
   }
   g_list_foreach(window_list, (GFunc)g_object_unref, NULL);
   g_list_free(window_list);
 }
 
-}  // namespace browser
+}  // namespace chrome