Move PageTransition into content namespace. While I'm touching all these files, I've also updated...

chrome/browser/ui/gtk/instant_confirm_dialog_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/instant_confirm_dialog_gtk.h"
 
 #include <gtk/gtk.h>
 
 #include "chrome/browser/instant/instant_confirm_dialog.h"
 #include "chrome/browser/instant/instant_controller.h"
@@ skipping 58 matching lines @@
     InstantController::Enable(profile_);
 
   delete this;
 }
 
 void InstantConfirmDialogGtk::OnLinkButtonClicked(GtkWidget* button) {
   // We open a new browser window so the Options dialog doesn't get lost behind
   // other windows.
   Browser* browser = Browser::Create(profile_);
   browser->AddSelectedTabWithURL(browser::InstantLearnMoreURL(),
-                                 PageTransition::LINK);
+                                 content::PAGE_TRANSITION_LINK);
   browser->window()->Show();
 }