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

remoting/webapp/clipboard_event_proto.js

Index: remoting/webapp/clipboard_event_proto.js
diff --git a/remoting/webapp/clipboard_event_proto.js b/remoting/webapp/clipboard_event_proto.js
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index 0000000000000000000000000000000000000000..8a95bb668b26ce15d00dbb0faa4b3eea1a411008
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+++ b/remoting/webapp/clipboard_event_proto.js
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+// 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.
+
+// This file contains type definitions for the remoting.ClipboardEvent class,
+// which is a subclass of Event.
+// It is used only with JSCompiler to verify the type-correctness of our code.
+
+/** @suppress {duplicate} */
+var remoting = remoting || {};
+
+/** @constructor
+ *  @extends Event
+ */
+remoting.ClipboardData = function() {};
+
+/** @type {Array.<string>} */
+remoting.ClipboardData.prototype.types;
+
+/** @type {function(string): string} */
+remoting.ClipboardData.prototype.getData;
+
+/** @constructor
+ */
+remoting.ClipboardEvent = function() {};
+
+/** @type {remoting.ClipboardData} */
+remoting.ClipboardEvent.prototype.clipboardData;