Refactor the devserver to make it easier to control caching

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

 # 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.
 
 import copy
 import json
 import logging
 
 import compiled_file_system as compiled_fs
 from file_system import FileNotFoundError
 from third_party.json_schema_compiler.model import UnixName
 
+# Increment this if the data model changes for SidenavDataSource.
+_VERSION = 1
+
 class SidenavDataSource(object):
   """This class reads in and caches a JSON file representing the side navigation
   menu.
   """
   class Factory(object):
-    def __init__(self, cache_factory, json_path):
-      self._cache = cache_factory.Create(self._CreateSidenavDict,
-                                         compiled_fs.SIDENAV)
+    def __init__(self, compiled_fs_factory, json_path):
+      self._cache = compiled_fs_factory.Create(self._CreateSidenavDict,
+                                               SidenavDataSource,
+                                               version=_VERSION)
       self._json_path = json_path
 
     def Create(self, path):
       """Create a SidenavDataSource, binding it to |path|. |path| is the url
       of the page that is being rendered. It is used to determine which item
       in the sidenav should be highlighted.
       """
       return SidenavDataSource(self._cache, self._json_path, path)
 
     def _AddLevels(self, items, level):
@@ skipping 27 matching lines @@
     return False
 
   def get(self, key):
     try:
       sidenav = copy.deepcopy(self._cache.GetFromFile(
           '%s/%s_sidenav.json' % (self._json_path, key)))
       self._AddSelected(sidenav)
       return sidenav
     except FileNotFoundError as e:
       logging.error('%s: Error reading sidenav "%s".' % (e, key))