Add CachingFileSystem on top of CloudStorageFileSystem

chrome/common/extensions/docs/server2/gcs_file_system_provider.py

 # Copyright 2014 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.
 
 import os
 import environment
 
+from caching_file_system import CachingFileSystem
 from empty_dir_file_system import EmptyDirFileSystem
 from extensions_paths import LOCAL_GCS_DIR, LOCAL_GCS_DEBUG_CONF
 from local_file_system import LocalFileSystem
 from path_util import IsDirectory
 
 class CloudStorageFileSystemProvider(object):
   '''Provides CloudStorageFileSystem bound to a GCS bucket.
   '''
   def __init__(self, object_store_creator):
     self._object_store_creator = object_store_creator
@@ skipping 56 matching lines @@
       use_local_fs = properties.get('use_local_fs', 'False')=='True'
       debug_access_token = properties.get('access_token', None)
       debug_bucket_prefix = properties.get('remote_bucket_prefix', None)
 
     if environment.IsDevServer() and use_local_fs:
       return LocalFileSystem(os.path.join(LOCAL_GCS_DIR, bucket))
 
     # gcs_file_system has strong dependencies on runtime appengine APIs,
     # so we only import it when we are sure we are not on preview.py or tests.
     from gcs_file_system import CloudStorageFileSystem
-    return CloudStorageFileSystem(
-        bucket, debug_access_token, debug_bucket_prefix)
-
+    return CachingFileSystem(CloudStorageFileSystem(bucket,
+        debug_access_token, debug_bucket_prefix),
+        self._object_store_creator)
 
   @staticmethod
   def ForEmpty():
     class EmptyImpl(object):
       def Create(self, bucket):
         return EmptyDirFileSystem()
     return EmptyImpl()