Cleanup: Remove unneeded includes of pref_names.h

chrome/browser/extensions/external_policy_extension_provider.cc

 // Copyright (c) 2010 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/extensions/external_policy_extension_provider.h"
 
+#include <string>
+
 #include "base/logging.h"
 #include "base/values.h"
-#include "chrome/common/pref_names.h"
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/extensions/stateful_external_extension_provider.h"
 #include "chrome/browser/prefs/pref_service.h"
 
 namespace {
 
 // Check an extension ID and an URL to be syntactically correct.
 bool CheckExtension(std::string id, std::string update_url) {
   GURL url(update_url);
   if (!url.is_valid()) {
     LOG(WARNING) << "Policy specifies invalid update URL for external "
                  << "extension: " << update_url;
     return false;
   }
   if (!Extension::IdIsValid(id)) {
     LOG(WARNING) << "Policy specifies invalid ID for external "
                  << "extension: " << id;
     return false;
   }
   return true;
 }
 
-}
+}  // namespace
 
 ExternalPolicyExtensionProvider::ExternalPolicyExtensionProvider(
     const ListValue* forcelist)
         : StatefulExternalExtensionProvider(
             Extension::INVALID,
             Extension::EXTERNAL_POLICY_DOWNLOAD) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   ProcessPreferences(forcelist);
 }
 
@@ skipping 24 matching lines @@
         std::string id = extension_desc.substr(0, pos);
         std::string update_url = extension_desc.substr(pos+1);
         if (CheckExtension(id, update_url)) {
           result->SetString(id + ".external_update_url", update_url);
         }
       }
     }
   }
   set_prefs(result);
 }