Docserver: Default to master commit ID on refresh

chrome/common/extensions/docs/server2/refresh_servlet.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 traceback
 
 from app_yaml_helper import AppYamlHelper
 from appengine_wrappers import IsDeadlineExceededError, logservice, taskqueue
 from branch_utility import BranchUtility
 from commit_tracker import CommitTracker
@@ skipping 72 matching lines @@
       commit = self._request.arguments['commit']
     else:
       _log.warning('No commit given; refreshing from master. '
                    'This is probably NOT what you want.')
       commit = None
 
     server_instance = self._CreateServerInstance(commit)
     commit_tracker = CommitTracker(server_instance.object_store_creator)
     refresh_tracker = RefreshTracker(server_instance.object_store_creator)
 
+    # If no commit was given, use the ID of the last cached master commit.
+    # This allows sources external to the chromium repository to be updated
+    # independently from individual refresh cycles.
+    if commit is None:
+      commit = commit_tracker.Get('master').Get()
+
     success = True
     try:
       if source_name == 'platform_bundle':
         data_source = server_instance.platform_bundle
       elif source_name == 'content_providers':
         data_source = server_instance.content_providers
       else:
         data_source = CreateDataSource(source_name, server_instance)
 
       class_name = data_source.__class__.__name__
@@ skipping 45 matching lines @@
     github_file_system_provider = self._delegate.CreateGithubFileSystemProvider(
         object_store_creator)
     gcs_file_system_provider = self._delegate.CreateGCSFileSystemProvider(
         object_store_creator)
     return ServerInstance(object_store_creator,
                           CompiledFileSystem.Factory(object_store_creator),
                           branch_utility,
                           host_file_system_provider,
                           github_file_system_provider,
                           gcs_file_system_provider)