chrome_paths: refactor and sanitize cache directory handling

chrome/common/chrome_paths_internal.h

 // 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.
 
 #ifndef CHROME_COMMON_CHROME_PATHS_INTERNAL_H_
 #define CHROME_COMMON_CHROME_PATHS_INTERNAL_H_
 #pragma once
 
 #include "build/build_config.h"
 
 class FilePath;
 
 namespace chrome {
 
 // Get the path to the user's data directory, regardless of whether
 // DIR_USER_DATA has been overridden by a command-line option.
 bool GetDefaultUserDataDirectory(FilePath* result);
 
 // This returns the base directory in which Chrome Frame stores user profiles.
 // Note that this cannot be wrapped in a preprocessor define since
 // CF and Google Chrome want to share the same binaries.
 bool GetChromeFrameUserDataDirectory(FilePath* result);
 
+// Get the path to the user's cache directory.  This is normally the
+// same as the profile directory, but on Linux it can also be
+// $XDG_CACHE_HOME and on Mac it can be under ~/Library/Caches.
+// Note that the Chrome cache directories are actually subdirectories
+// of this directory, with names like "Cache" and "Media Cache".
+// This will always fill in |result| with a directory, sometimes
+// just |profile_dir|.
+void GetUserCacheDirectory(const FilePath& profile_dir, FilePath* result);
+
 // Get the path to the user's documents directory.
 bool GetUserDocumentsDirectory(FilePath* result);
 
 #if defined (OS_WIN)
 // Gets the path to a safe default download directory for a user.
 bool GetUserDownloadsDirectorySafe(FilePath* result);
 #endif
 
 // Get the path to the user's downloads directory.
 bool GetUserDownloadsDirectory(FilePath* result);
@@ skipping 23 matching lines @@
 FilePath GetFrameworkBundlePath();
 
 // Get the local library directory.
 bool GetLocalLibraryDirectory(FilePath* result);
 
 #endif  // OS_MACOSX
 
 }  // namespace chrome
 
 #endif  // CHROME_COMMON_CHROME_PATHS_INTERNAL_H_