gdata: Support mounting archive files in GData cache.

chrome/browser/chromeos/gdata/gdata_util.h

 // Copyright (c) 2012 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_BROWSER_CHROMEOS_GDATA_GDATA_UTIL_H_
 #define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_UTIL_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 44 matching lines @@
 
 // Grants read-only file access permissions to the process whose id is |pid|
 // with ChildProcessSecurityPolicy for all possible cache paths that may be
 // given to the specified file.
 void SetPermissionsForGDataCacheFiles(Profile* profile,
                                       int pid,
                                       const FilePath& path);
 
 // Returns true if gdata is currently active with the specified profile.
 bool IsGDataAvailable(Profile* profile);
+
+// Extracts resource_id, md5, and extra_extension from cache path.
+// Case 1: Pinned and outgoing symlinks only have resource_id.
+// Example: path="/user/GCache/v1/pinned/pdf:a1b2" =>
+//          resource_id="pdf:a1b2", md5="", extra_extension="";
+// Case 2: Normal files have both resource_id and md5.
+// Example: path="/user/GCache/v1/tmp/pdf:a1b2.01234567" =>
+//          resource_id="pdf:a1b2", md5="01234567", extra_extension="";
+// Case 3: Mounted files have all three parts.
+// Example: path="/user/GCache/v1/persistent/pdf:a1b2.01234567.mounted" =>
+//          resource_id="pdf:a1b2", md5="01234567", extra_extension="mounted".
+void ParseCacheFilePath(const FilePath& path,
+                        std::string* resource_id,
+                        std::string* md5,
+                        std::string* extra_extension);
 }  // namespace util
 }  // namespace gdata
 
 #endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_UTIL_H_