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

remoting/client/mouse_input_filter.cc

Index: remoting/client/mouse_input_filter.cc
diff --git a/remoting/client/mouse_input_filter.cc b/remoting/client/mouse_input_filter.cc
index 00d981d0c97df916cd56107615991c707255d432..2516f1e5feee43aad125e9345ae767dc3e7d5b30 100644
--- a/remoting/client/mouse_input_filter.cc
+++ b/remoting/client/mouse_input_filter.cc
@@ -17,6 +17,11 @@ MouseInputFilter::MouseInputFilter(protocol::InputStub* input_stub)
 MouseInputFilter::~MouseInputFilter() {
 }
 
+void MouseInputFilter::InjectClipboardEvent(
+    const protocol::ClipboardEvent& event) {
+  input_stub_->InjectClipboardEvent(event);
+}
+
 void MouseInputFilter::InjectKeyEvent(const protocol::KeyEvent& event) {
   input_stub_->InjectKeyEvent(event);
 }