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

content/common/request_extra_data.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 "content/common/request_extra_data.h"
 
 RequestExtraData::RequestExtraData(bool is_main_frame,
                                    int64 frame_id,
-                                   PageTransition::Type transition_type)
+                                   content::PageTransition transition_type)
     : is_main_frame_(is_main_frame),
       frame_id_(frame_id),
       transition_type_(transition_type) {
 }
 
 RequestExtraData::~RequestExtraData() {
 }