Add an API to get total size of Drive cache including non-evictable ones.

components/drive/chromeos/dummy_file_system.h

 // Copyright 2013 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 COMPONENTS_DRIVE_CHROMEOS_DUMMY_FILE_SYSTEM_H_
 #define COMPONENTS_DRIVE_CHROMEOS_DUMMY_FILE_SYSTEM_H_
 
 #include <stdint.h>
 
 #include "components/drive/chromeos/file_system_interface.h"
@@ skipping 86 matching lines @@
                    google_apis::drive::Property::Visibility visibility,
                    const std::string& key,
                    const std::string& value,
                    const FileOperationCallback& callback) override {}
   void Reset(const FileOperationCallback& callback) override {}
   void GetPathFromResourceId(const std::string& resource_id,
                              const GetFilePathCallback& callback) override {}
   void FreeDiskSpaceIfNeededFor(
       int64_t num_bytes,
       const FreeDiskSpaceCallback& callback) override {}
+  void CalculateCacheSize(const CacheSizeCallback& callback) override {}
   void CalculateEvictableCacheSize(
-      const EvictableCacheSizeCallback& callback) override {}
+      const CacheSizeCallback& callback) override {}
 };
 
 }  // namespace drive
 
 #endif  // COMPONENTS_DRIVE_CHROMEOS_DUMMY_FILE_SYSTEM_H_