Add touch events to the protocol, the stub layer, and to the client plugin.

remoting/protocol/input_event_tracker.h

Index: remoting/protocol/input_event_tracker.h
diff --git a/remoting/protocol/input_event_tracker.h b/remoting/protocol/input_event_tracker.h
index e167cd2bb16688b073b8c23918dc660c35b07633..24ff23763cb8805bbea03b7431f0b65789924e87 100644
--- a/remoting/protocol/input_event_tracker.h
+++ b/remoting/protocol/input_event_tracker.h
@@ -37,6 +37,7 @@ class InputEventTracker : public InputStub {
   void InjectKeyEvent(const KeyEvent& event) override;
   void InjectTextEvent(const TextEvent& event) override;
   void InjectMouseEvent(const MouseEvent& event) override;
+  void InjectTouchEvent(const TouchEvent& event) override;
 
  private:
   protocol::InputStub* input_stub_;