[Media Router] Add a context menu item to access the chrome://cast page

chrome/app/media_router_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Media Router-specific strings (included from generated_resources.grd). -->
 <grit-part>
   <!-- General -->
   <message name="IDS_MEDIA_ROUTER_TITLE" desc="Title of a dialog offering possible actions for Media Router, which enables users to mirror individual tabs or desktop as well as cast content to a device.">
     Media Router
   </message>
   <message name="IDS_MEDIA_ROUTER_ICON_TOOLTIP_TEXT" desc="Tooltip for the Media Router Action icon, which appears in the toolbar. The tooltip appears on mouseover of the icon.">
    Display on another screen
   </message>
@@ skipping 51 matching lines @@
     <message name="IDS_MEDIA_ROUTER_CLOUD_SERVICES_TOGGLE" desc="Title of a menu item which, on click, toggles the preference to opt in or out of cloud services.">
      Enable Cloud Services
     </message>
   </if>
   <message name="IDS_MEDIA_ROUTER_HELP" desc="Title of a menu item which, on click, opens a page to the Chromecast help center.">
    Help
   </message>
   <message name="IDS_MEDIA_ROUTER_REPORT_ISSUE" desc="Title of a menu item which, on click, opens a page to give feedback or report an issue with Chromecast integration.">
    Report an issue
   </message>
+  <message name="IDS_MEDIA_ROUTER_MANAGE_DEVICES" desc="Title of a menu item which, on click, opens a page that allows the user to manage Cast devices: view, reboot, reset, and manage settings of available Cast devices, or set up new Cast devices.">
+   Manage Cast devices
+  </message>
 
   <!-- First Run Flow -->
   <if expr="_google_chrome">
     <message name="IDS_MEDIA_ROUTER_FIRST_RUN_FLOW_CLOUD_PREF_TEXT" desc="Text of the cloud services preferences text in the first run flow, which is shown to the user if they are currently signed in and have enabled sync.">
       Enable casting to cloud-based services like Google Hangouts.
     </message>
     <message name="IDS_MEDIA_ROUTER_FIRST_RUN_FLOW_TITLE" desc="Title of the first run flow, which is shown to the user the first time they use Media Router, until they acknowledge the message. This is a welcome message that introduces Media Router to the user.">
       Welcome to the Cast experience in Chrome!
     </message>
     <message name="IDS_MEDIA_ROUTER_FIRST_RUN_FLOW_TEXT" desc="Text of the first run flow, which is shown to the user the first time they use Media Router. This is an introductory description of what Media Router does.">
@@ skipping 54 matching lines @@
   </message>
 
   <!-- Sink Search -->
   <message name="IDS_MEDIA_ROUTER_SEARCH_LABEL" desc="Label for search input in sink list.">
     Search
   </message>
   <message name="IDS_MEDIA_ROUTER_SEARCH_NO_MATCHES" desc="Text to display when there are no sinks matching the user input search text.">
     No matches
   </message>
 </grit-part>