Use Drive v2 API: enable behind --enable-drive-api flag

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 75 matching lines @@
 // 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);
+
+// Returns true if Drive v2 API is enabled via commandline switch.
+bool IsDriveV2ApiEnabled();
+
 }  // namespace util
 }  // namespace gdata
 
 #endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_UTIL_H_