clean up message "External extension with id xxxx has been uninstalled by ..."

extensions/browser/extension_prefs.cc

 // Copyright 2014 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 "extensions/browser/extension_prefs.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <iterator>
@@ skipping 1241 matching lines @@
     const std::string& extension_id) const {
   const base::DictionaryValue* ext = NULL;
   const base::DictionaryValue* extensions =
       prefs_->GetDictionary(pref_names::kExtensions);
   if (!extensions ||
       !extensions->GetDictionaryWithoutPathExpansion(extension_id, &ext))
     return std::unique_ptr<ExtensionInfo>();
   int state_value;
   if (ext->GetInteger(kPrefState, &state_value) &&
       state_value == Extension::EXTERNAL_EXTENSION_UNINSTALLED) {
-    LOG(WARNING) << "External extension with id " << extension_id
-                 << " has been uninstalled by the user";
     return std::unique_ptr<ExtensionInfo>();
   }
 
   return GetInstalledInfoHelper(extension_id, ext);
 }
 
 std::unique_ptr<ExtensionPrefs::ExtensionsInfo>
 ExtensionPrefs::GetInstalledExtensionsInfo() const {
   std::unique_ptr<ExtensionsInfo> extensions_info(new ExtensionsInfo);
 
@@ skipping 711 matching lines @@
   extension_pref_value_map_->RegisterExtension(
       extension_id, install_time, is_enabled, is_incognito_enabled);
 
   FOR_EACH_OBSERVER(
       ExtensionPrefsObserver,
       observer_list_,
       OnExtensionRegistered(extension_id, install_time, is_enabled));
 }
 
 }  // namespace extensions