Implement chrome.downloads.onDeterminingFilename()

WATCHLISTS

 # 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.
 
 # Watchlist Rules
 # Refer: http://dev.chromium.org/developers/contributing-code/watchlists
 
 # IMPORTANT: The regular expression filepath is tested against each path using
 # re.search, so it is not usually necessary to add .*.
 
@@ skipping 174 matching lines @@
       'filepath': 'chrome/browser/resources/options/|'\
                   'chrome/browser/resources/options.html|'\
                   'chrome/browser/ui/webui/options/',
     },
     'download': {
       'filepath': 'chrome/browser/download/|'\
                   'content/browser/download/',
     },
     'downloads_ext': {
       'filepath': 'chrome/browser/extensions/api/downloads/|'\
-                  'chrome/common/extensions/api/downloads.idl',
+                  'chrome/common/extensions/api/downloads.*.idl',
     },
     'downloads_ui': {
       'filepath': 'chrome/browser/resources/downloads/|' \
                   'chrome/browser/ui/webui/.*downloads|' \
                   'chrome/browser/ui/views/download/|' \
                   'chrome/browser/ui/cocoa/download/|' \
                   'chrome/browser/ui/gtk/download/'
     },
     'drive': {
       'filepath': 'chrome/browser/chromeos/drive/|' \
@@ skipping 500 matching lines @@
                    'groby+watch@chromium.org',
                    'rouslan+watch@chromium.org'],
     'website_settings': ['markusheintz@chromium.org'],
     'webkit': ['darin-cc@chromium.org'],
     'worker': ['jam@chromium.org'],
     'x11': ['derat+watch@chromium.org',
             'sadrul@chromium.org',
             'yusukes+watch@chromium.org'],
   },
 }