Add the plumbing that will carry a clipboard item from a chromoting client to a host.

remoting/host/client_session.cc

Index: remoting/host/client_session.cc
diff --git a/remoting/host/client_session.cc b/remoting/host/client_session.cc
index 6ff6164add558a5ff006bc22d5a38b0f5ea16f77..d41f41fda173a2ba1107ee5b203d50792c85b69c 100644
--- a/remoting/host/client_session.cc
+++ b/remoting/host/client_session.cc
@@ -28,11 +28,13 @@ using protocol::MouseEvent;
 ClientSession::ClientSession(
     EventHandler* event_handler,
     protocol::ConnectionToClient* connection,
+    protocol::ClipboardStub* clipboard_stub,
     protocol::InputStub* input_stub,
     Capturer* capturer)
     : event_handler_(event_handler),
       connection_(connection),
       client_jid_(connection->session()->jid()),
+      clipboard_stub_(clipboard_stub),
       input_stub_(input_stub),
       capturer_(capturer),
       authenticated_(false),
@@ -43,6 +45,7 @@ ClientSession::ClientSession(
   // TODO(sergeyu): Currently ConnectionToClient expects stubs to be
   // set before channels are connected. Make it possible to set stubs
   // later and set them only when connection is authenticated.
+  connection_->set_clipboard_stub(this);
   connection_->set_host_stub(this);
   connection_->set_input_stub(this);
 }
@@ -50,6 +53,15 @@ ClientSession::ClientSession(
 ClientSession::~ClientSession() {
 }
 
+void ClientSession::InjectClipboardEvent(
+    const protocol::ClipboardEvent& event) {
+  DCHECK(CalledOnValidThread());
+
+  if (authenticated_) {
+    clipboard_stub_->InjectClipboardEvent(event);
+  }
+}
+
 void ClientSession::InjectKeyEvent(const KeyEvent& event) {
   DCHECK(CalledOnValidThread());