[Chromoting] Let the webapp detect new clipboard text items when it gets focus.

remoting/webapp/clipboard.js

+// Copyright (c) 2012 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.
+
+/**
+ * @fileoverview
+ * A class for moving clipboard items between the plugin and the OS.
+ */
+
+'use strict';
+
+/** @suppress {duplicate} */
+var remoting = remoting || {};
+
+/**
+ * @constructor
+ */
+remoting.Clipboard = function() {
+};
+
+/**
+ * @private
+ * @enum {string}
+ */
+remoting.Clipboard.prototype.ItemTypes = {
+  TEXT_TYPE: 'text/plain'
+};
+
+/**
+ * @private
+ * @type {string}
+ */
+remoting.Clipboard.prototype.recentItemText = "";
+
+/**
+ * Accepts a clipboard from the OS, and sends any changed clipboard items to
+ * the host.
+ *
+ * Currently only text items are supported.
+ *
+ * @param {remoting.ClipboardData} clipboardData
+ * @return {void} Nothing.
+ */
+remoting.Clipboard.prototype.toHost = function(clipboardData) {
+  if (!clipboardData || !clipboardData.types || !clipboardData.getData) {
+    return;
+  }
+  var textType = 'text/plain';
+  for (var i = 0; i < clipboardData.types.length; i++) {
+    var type = clipboardData.types[i];
+    if (type == this.ItemTypes.TEXT_TYPE) {
+      var item = clipboardData.getData(type);
+      if (!item) {
+        item = "";
+      }
+      if (item != this.recentItemText) {
+        // TODO(simonmorris): Pass the clipboard text item to the plugin.
+        this.recentItemText = item;
+      }
+    }
+  }
+};
+
+/** @type {remoting.Clipboard} */
+remoting.clipboard = null;