mock_platform: fix argument count for GetGroupId mock

mock_platform.h

 // Copyright (c) 2011 The Chromium OS 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 CRYPTOHOME_MOCK_PLATFORM_H_
 #define CRYPTOHOME_MOCK_PLATFORM_H_
 
 #include "mount.h"
 
 #include <gmock/gmock.h>
@@ skipping 20 matching lines @@
                            const std::string&, const std::string&));
   MOCK_METHOD3(Unmount, bool(const std::string&, bool, bool*));
   MOCK_METHOD1(IsDirectoryMounted, bool(const std::string&));
   MOCK_METHOD2(IsDirectoryMountedWith, bool(const std::string&,
                                             const std::string&));
   MOCK_METHOD2(TerminatePidsWithOpenFiles, bool(const std::string&, bool));
   MOCK_METHOD2(TerminatePidsForUser, bool(const uid_t, bool));
   MOCK_METHOD3(SetOwnership, bool(const std::string&, uid_t, gid_t));
   MOCK_METHOD3(SetOwnershipRecursive, bool(const std::string&, uid_t, gid_t));
   MOCK_METHOD3(GetUserId, bool(const std::string&, uid_t*, gid_t*));
-  MOCK_METHOD3(GetGroupId, bool(const std::string&, gid_t*));
+  MOCK_METHOD2(GetGroupId, bool(const std::string&, gid_t*));
   MOCK_CONST_METHOD1(AmountOfFreeDiskSpace, int64(const std::string&));
   MOCK_METHOD2(Symlink, bool(const std::string&, const std::string&));
   MOCK_METHOD4(Exec, bool(const std::string&, const std::vector<std::string>&,
                           uid_t, gid_t));
 
  private:
   bool MockGetUserId(const std::string& user, uid_t* user_id, gid_t* group_id) {
     *user_id = getuid();
     *group_id = getgid();
     return true;
   }
 };
 }  // namespace cryptohome
 
 #endif  // CRYPTOHOME_MOCK_PLATFORM_H_