Port downloads.ItemView to a Polymer component.

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/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/cr/ui.js',
           '../../../../ui/webui/resources/js/cr/ui/command.js',
           '../../../../ui/webui/resources/js/util.js',
+          '../downloads/constants.js',
+          '../downloads/icon_loader.js',
+          'item_view.js',
         ],
         'externs': [
           '<(EXTERNS_DIR)/chrome_send.js',
           '../downloads/externs.js',
         ],
       },
       'includes': ['../../../../third_party/closure_compiler/compile_js.gypi'],
     }
   ],
 }