[MD Extensions] Move search field out of downloads, use it in extensions

chrome/browser/resources/md_downloads/compiled_resources.gyp

 # Copyright 2015 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.
 {
   'targets': [
     {
       'target_name': 'manager',
       'variables': {
         'depends': [
+          '../../../../ui/webui/resources/cr_elements/v1_0/cr_search_field/cr_search_field.js',
           '../../../../ui/webui/resources/js/action_link.js',
           '../../../../ui/webui/resources/js/assert.js',
           '../../../../ui/webui/resources/js/compiled_resources.gyp:load_time_data',
           '../../../../ui/webui/resources/js/cr.js',
           '../../../../ui/webui/resources/js/event_tracker.js',
           '../../../../ui/webui/resources/js/cr/ui.js',
           '../../../../ui/webui/resources/js/cr/ui/command.js',
           '../../../../ui/webui/resources/js/cr/ui/focus_row.js',
           '../../../../ui/webui/resources/js/cr/ui/focus_grid.js',
           '../../../../ui/webui/resources/js/util.js',
           '../downloads/constants.js',
           '../downloads/throttled_icon_loader.js',
           'action_service.js',
           'focus_row.js',
           'item.js',
           'toolbar.js',
         ],
         'externs': [
           '<(EXTERNS_DIR)/chrome_send.js',
           '../downloads/externs.js',
         ],
       },
       'includes': ['../../../../third_party/closure_compiler/compile_js.gypi'],
     }
   ],
 }