Show data usage on Site Details (MDSettings)

chrome/browser/resources/settings/site_settings/site_settings_handler.js

+// Copyright 2016 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.
+
+/**
+ * @constructor
+ */
+function SiteSettingsHandler() {}
+
+/**
+ * Asynchronously fetches the total amount of data attributed to a given origin.
+ * If no data is attributed to the origin, the callback does not fire.
+ * @param {string} origin The origin to look up.
+ * @param {!Element} context The context to use for the callback.
+ * @param {Function=} callback The callback to run when the data is ready.

[michaelpg, 2016/01/19 20:47:54]

uncapitalize function, and have it take a string: {function(string)}

the "=" means "optional": if this is really optional, rename to opt_callback.

[Finnur, 2016/01/22 15:07:35]

Done.

+ */
+SiteSettingsHandler.prototype.fetchUsageTotal = function(
+    origin, context, callback) {
+  this.context = context;
+  this.callback = callback;
+
+  var self = this;
+  cr.define('SiteSettingsHandler', function() {
+    return {
+      OnUsageDataAvailable: function() {
+        return self.returnUsageTotal.apply(self, arguments);
+      },
+    };
+  });
+
+  chrome.send('fetchUsageTotal', [origin]);
+};
+
+/**
+ * Handles reporting the amount (of usage data) back to the caller.
+ * @param {string} usage The total amount of data attributed to a given origin.
+ */
+SiteSettingsHandler.prototype.returnUsageTotal = function(usage) {
+  this.callback.call(this.context, usage);
+};

[Finnur, 2016/01/19 17:08:57]

Is all of the above a reasonable way to do this abstraction layer or is there a
better way?

[michaelpg, 2016/01/19 20:47:54]

I would make SiteSettingsHandler "static" and simplify the callback structure.
+stevenjb for his thoughts.

[Finnur, 2016/01/22 15:07:35]

Obsolete code now.