Makes GetComponentExtensionResourceManager() thread-safe.

chrome/browser/extensions/chrome_component_extension_resource_manager.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 "chrome/browser/extensions/chrome_component_extension_resource_manager.h"
 
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "chrome/common/chrome_paths.h"
 #include "grit/chrome_unscaled_resources.h"
@@ skipping 47 matching lines @@
       keyboard_resource_size);
 #endif
 }
 
 ChromeComponentExtensionResourceManager::
 ~ChromeComponentExtensionResourceManager() {}
 
 bool ChromeComponentExtensionResourceManager::IsComponentExtensionResource(
     const base::FilePath& extension_path,
     const base::FilePath& resource_path,
-    int* resource_id) {
+    int* resource_id) const {
   base::FilePath directory_path = extension_path;
   base::FilePath resources_dir;
   base::FilePath relative_path;
   if (!PathService::Get(chrome::DIR_RESOURCES, &resources_dir) ||
       !resources_dir.AppendRelativePath(directory_path, &relative_path)) {
     return false;
   }
   relative_path = relative_path.Append(resource_path);
   relative_path = relative_path.NormalizePathSeparators();
 
@@ skipping 13 matching lines @@
         entries[i].name);
     resource_path = resource_path.NormalizePathSeparators();
 
     DCHECK(path_to_resource_id_.find(resource_path) ==
         path_to_resource_id_.end());
     path_to_resource_id_[resource_path] = entries[i].value;
   }
 }
 
 }  // namespace extensions