Reland: Allow high-res bitmaps to be passed in from notifications API.

chrome/renderer/resources/extensions/notifications_test_util.js

+// Copyright 2014 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.
+
+// NotificationsTestUtil contains stubs for the global classes and
+// variables used by notifications_custom_bindings.js that are not
+// available with gtestjs tests.
+var require = function(library) {
+  return {
+    binding: {
+      'Binding': {
+        'create': function () {
+          return {
+            registerCustomHook: function () {},
+            generate: function () {}
+          };
+        }
+      }
+    },
+    sendRequest: {
+      sendRequest: function () {}
+    },
+  }[library];
+};
+
+var requireNative = function(library) {
+  return {
+    notifications_private: {
+      GetNotificationImageSizes: function () {
+        return {
+          scaleFactor: 0,
+          icon: { width: 0, height: 0 },
+          image: { width: 0, height: 0 },
+          buttonIcon: { width: 0, height: 0}
+        };
+      }
+    }
+  }[library];
+}
+
+var exports = {};
+
+var $Array = {
+  push: function (ary, val) {
+    ary.push(val);
+  }
+};
+
+var $Function = {
+  bind: function (fn, context) {
+    return fn.bind(context);
+  }
+};