[Media Router WebUI] Use I18nBehavior to retrieve strings.

chrome/browser/resources/media_router/elements/route_details/route_details.js

Index: chrome/browser/resources/media_router/elements/route_details/route_details.js
diff --git a/chrome/browser/resources/media_router/elements/route_details/route_details.js b/chrome/browser/resources/media_router/elements/route_details/route_details.js
index 5d755af452ee5321f90053f0159e943248ccfc8b..2689de1a581aa4994a279b34ea9e5f64a6c93955 100644
--- a/chrome/browser/resources/media_router/elements/route_details/route_details.js
+++ b/chrome/browser/resources/media_router/elements/route_details/route_details.js
@@ -18,27 +18,6 @@ Polymer({
     },
 
     /**
-     * The localized strings used by |this|.
-     * @private {!Object}
-     */
-    i18n_: {
-      readOnly: true,
-      type: Object,
-      value: function() {
-        var strings = {};
-        [
-          'startCastingButtonText',
-          'stopCastingButtonText',
-          'dropDownButtonTitle',
-        ]
-        .forEach(function(s) {
-          strings[s] = loadTimeData.getString(s);
-        });
-        return strings;
-      },
-    },
-
-    /**
      * The route to show.
      * @type {?media_router.Route}
      */
@@ -60,6 +39,10 @@ Polymer({
     },
   },
 
+  behaviors: [
+    I18nBehavior,
+  ],
+
   /**
    * Fires a close-route-click event. This is called when the button to close
    * the current route is clicked.