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

chrome/browser/platform_util_chromeos.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/platform_util.h"
 
 #include "base/file_util.h"
 #include "base/process_util.h"
 #include "base/task.h"
 #include "base/utf_string_conversions.h"
@@ skipping 47 matching lines @@
         NewRunnableFunction(&OpenFileBrowserOnUIThread, dir));
   }
 }
 
 void OpenItem(const FilePath& full_path) {
   FileManagerUtil::ViewItem(full_path, false);
 }
 
 static void OpenURL(const std::string& url) {
   Browser* browser = BrowserList::GetLastActive();
-  browser->AddSelectedTabWithURL(GURL(url), PageTransition::LINK);
+  browser->AddSelectedTabWithURL(GURL(url), content::PAGE_TRANSITION_LINK);
 }
 
 void OpenExternal(const GURL& url) {
   if (url.SchemeIs("mailto")) {
     std::string string_url = kGmailComposeUrl;
     string_url.append(url.spec());
     BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE, NewRunnableFunction(OpenURL, string_url));
   }
 }
 
 }  // namespace platform_util