chrome_paths: refactor and sanitize cache directory handling

base/path_service.h

 // Copyright (c) 2006-2008 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.
 
 #ifndef BASE_PATH_SERVICE_H_
 #define BASE_PATH_SERVICE_H_
 #pragma once
 
 #include "build/build_config.h"
 
@@ skipping 27 matching lines @@
   // path specifies a directory that does not exist, the directory will be
   // created by this method.  This method returns true if successful.
   //
   // If the given path is relative, then it will be resolved against
   // DIR_CURRENT.
   //
   // WARNING: Consumers of PathService::Get may expect paths to be constant
   // over the lifetime of the app, so this method should be used with caution.
   static bool Override(int key, const FilePath& path);
 
-  // Return whether a path was overridden.
-  // TODO(evan): temporarily restoring this to quick-fix a regression.
-  // Remove me again once it's fixed properly.
-  static bool IsOverridden(int key);
-
   // To extend the set of supported keys, you can register a path provider,
   // which is just a function mirroring PathService::Get.  The ProviderFunc
   // returns false if it cannot provide a non-empty path for the given key.
   // Otherwise, true is returned.
   //
   // WARNING: This function could be called on any thread from which the
   // PathService is used, so a the ProviderFunc MUST BE THREADSAFE.
   //
   typedef bool (*ProviderFunc)(int, FilePath*);
 
   // Call to register a path provider.  You must specify the range "[key_start,
   // key_end)" of supported path keys.
   static void RegisterProvider(ProviderFunc provider,
                                int key_start,
                                int key_end);
  private:
   static bool GetFromCache(int key, FilePath* path);
   static bool GetFromOverrides(int key, FilePath* path);
   static void AddToCache(int key, const FilePath& path);
 };
 
 #endif  // BASE_PATH_SERVICE_H_