Implement test-echo extension message and reply.

TEST=Run the following command in the JS console once connected: remoting.clientSession.plugin.sendExtensionMessage('test-echo', <thing to be echoed>)

Review URL: https://chromiumcodereview.appspot.com/23491004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@220802 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/remoting/host/client_session.cc b/remoting/host/client_session.cc
index b001a39..45439f4 100644
--- a/remoting/host/client_session.cc
+++ b/remoting/host/client_session.cc
@@ -189,6 +189,16 @@
 
 void ClientSession::DeliverClientMessage(
     const protocol::ExtensionMessage& message) {
+  if (message.has_type()) {
+    if (message.type() == "test-echo") {
+      protocol::ExtensionMessage reply;
+      reply.set_type("test-echo-reply");
+      if (message.has_data())
+        reply.set_data(message.data().substr(0, 16));
+      connection_->client_stub()->DeliverHostMessage(reply);
+      return;
+    }
+  }
   // No messages are currently supported.
   LOG(INFO) << "Unexpected message received: "
             << message.type() << ": " << message.data();