Move platform-specific functionality into Platform

Platform classes are provided by the application via
PlatformPeg.set().

src/BasePlatform.js

@@ -0,0 +1,41 @@
+// @flow
+
+/*
+Copyright 2016 Aviral Dasgupta and OpenMarket Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/**
+ * Base class for classes that provide platform-specific functionality
+ * eg. Setting an application badge or displaying notifications
+ *
+ * Instances of this class are provided by the application.
+ */
+export default class BasePlatform {
+    constructor() {
+        this.notificationCount = 0;
+        this.errorDidOccur = false;
+    }
+
+    setNotificationCount(count: number) {
+        this.notificationCount = count;
+    }
+
+    setErrorStatus(errorDidOccur: boolean) {
+        this.errorDidOccur = errorDidOccur;
+    }
+
+    displayNotification(title: string, msg: string, avatarUrl: string) {
+    }
+}