Convert FieldTrialActivated to use mojo.

chrome/app/mash/chrome_mash_content_browser_manifest_overlay.json

 // NOTE: This overlay is applied to content_browser_manifest.json on top of
 // src/chrome/browser/chrome_content_browser_manifest_overlay.json.
 //
 // The resulting manifest is output to
 // ${out}/Packages/chrome_mash_content_browser/manifest.json and is used as the
 // manifest for "content_browser" (i.e. the browser process) when Chrome
 // is run in a Mash environment.
 {
   "interface_provider_specs": {
     "service_manager:connector": {
       "provides": {
         "ash": [
           "app_list::mojom::AppListPresenter"
         ],
-        "ime:ime_driver": [ "ui::mojom::IMEDriver" ]
+        "ime:ime_driver": [ "ui::mojom::IMEDriver" ],
+        "renderer": [

[Ken Rockot(use gerrit already), 2016/12/01 17:29:47]

this is redundant, please don't add it. this overlay is always applied on top of
the chrome_content_browser_manifest_overlay

[nigeltao1, 2016/12/04 01:24:01]

Done.

+          "chrome::mojom::FieldTrialRecorder"
+        ]
       },
       "requires": {
         "accessibility_autoclick": [ "ash:autoclick" ],
         "mash_session": [ "app" ],
         "task_viewer": [ "mash:launchable" ],
         "ui": [ "ui:ime_registrar" ]
       }
     }
   }
 }