[Webapp Refactor] Implements remoting.Activity.

remoting/webapp/crd/js/client_session.js

Index: remoting/webapp/crd/js/client_session.js
diff --git a/remoting/webapp/crd/js/client_session.js b/remoting/webapp/crd/js/client_session.js
index 12260801fad8053d2e6fb0a655279b660e8628ca..c4af96b28305e6827bd4090abbe1ee57d4be8529 100644
--- a/remoting/webapp/crd/js/client_session.js
+++ b/remoting/webapp/crd/js/client_session.js
@@ -92,10 +92,48 @@ remoting.ClientSession = function(plugin, host, signalStrategy,
 
 /** @enum {string} */
 remoting.ClientSession.Events = {
-  stateChanged: 'stateChanged',
+  stateChanged: 'stateChanged', // deprecated.
   videoChannelStateChanged: 'videoChannelStateChanged',
 };
 
+/**
+ * @interface
+ * [START]-------> [onConnected] ------> [onDisconnected]
+ *    |                              |
+ *    |-----> [OnConnectionFailed]   |----> [onError]
+ *
+ * TODO(kelvinp): Route session state changes through this interface.
+ */
+remoting.ClientSession.EventHandler = function() {};
+
+/**
+ * Called when the connection failed before it is connected.
+ *
+ * @param {!remoting.Error} error
+ */
+remoting.ClientSession.EventHandler.prototype.onConnectionFailed =
+    function(error) {};
+
+/**
+ * Called when a new session has been connected.  The |connectionInfo| will be
+ * valid until onDisconnected() or onError() is called.
+ *
+ * @param {!remoting.ConnectionInfo} connectionInfo
+ */
+remoting.ClientSession.EventHandler.prototype.onConnected =
+    function(connectionInfo) {};
+
+/**
+ * Called when the current session has been disconnected.
+ */
+remoting.ClientSession.EventHandler.prototype.onDisconnected = function() {};
+
+/**
+ * Called when an error needs to be displayed to the user.
+ * @param {!remoting.Error} error
+ */
+remoting.ClientSession.EventHandler.prototype.onError = function(error) {};
+
 // Note that the positive values in both of these enums are copied directly
 // from connection_to_host.h and must be kept in sync. Code in
 // chromoting_instance.cc converts the C++ enums into strings that must match
@@ -544,19 +582,6 @@ remoting.ClientSession.prototype.logHostOfflineErrors = function(enable) {
 };
 
 /**
- * Request pairing with the host for PIN-less authentication.
- *
- * @param {string} clientName The human-readable name of the client.
- * @param {function(string, string):void} onDone Callback to receive the
- *     client id and shared secret when they are available.
- */
-remoting.ClientSession.prototype.requestPairing = function(clientName, onDone) {
-  if (this.plugin_) {
-    this.plugin_.requestPairing(clientName, onDone);
-  }
-};
-
-/**
  * Sends a clipboard item to the host.
  *
  * @param {string} mimeType The MIME type of the clipboard item.