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

remoting/protocol/input_filter.h

Index: remoting/protocol/input_filter.h
diff --git a/remoting/protocol/input_filter.h b/remoting/protocol/input_filter.h
index 1b7c21179eb55ebd3b21e6b34a58eef2a0c29549..de032f2ea6ee69a7074cf459b7f15201f3971552 100644
--- a/remoting/protocol/input_filter.h
+++ b/remoting/protocol/input_filter.h
@@ -38,6 +38,7 @@ class InputFilter : 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:
   InputStub* input_stub_;