[Media Router WebUI] Update arrow drop title text to be more descriptive.

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

Index: chrome/browser/resources/media_router/elements/media_router_header/media_router_header.js
diff --git a/chrome/browser/resources/media_router/elements/media_router_header/media_router_header.js b/chrome/browser/resources/media_router/elements/media_router_header/media_router_header.js
index 8a3d32dd7fcb2a084fca6bda2141df8a17108aeb..fba24a5cb16208b2ca7e27e9e9e5b93f7862d416 100644
--- a/chrome/browser/resources/media_router/elements/media_router_header/media_router_header.js
+++ b/chrome/browser/resources/media_router/elements/media_router_header/media_router_header.js
@@ -51,18 +51,6 @@ Polymer({
     },
 
     /**
-     * Title text for the drop down button.
-     * @private {string}
-     */
-    dropDownButtonTitle_: {
-      type: String,
-      readOnly: true,
-      value: function() {
-        return loadTimeData.getString('dropDownButtonTitle');
-      },
-    },
-
-    /**
      * The header text to show.
      * @type {string}
      */
@@ -162,6 +150,17 @@ Polymer({
 
   /**
    * @param {?media_router.MediaRouterView} view The current view.
+   * @return {string} The title text for the arrow drop button.
+   * @private
+   */
+  computeArrowDropTitle_: function(view) {
+    return view == media_router.MediaRouterView.CAST_MODE_LIST ?
+        loadTimeData.getString('viewDeviceListButtonTitle') :
+            loadTimeData.getString('viewCastModeListButtonTitle');
+  },
+
+  /**
+   * @param {?media_router.MediaRouterView} view The current view.
    * @return {boolean} Whether or not the back button should be hidden.
    * @private
    */