chromeos: adds TouchDeviceServer and wires up in mushrome

ash/mus/bridge/shell_port_mash.h

Index: ash/mus/bridge/shell_port_mash.h
diff --git a/ash/mus/bridge/shell_port_mash.h b/ash/mus/bridge/shell_port_mash.h
index 967d78c1d697e1191ef419210c0cf10eaf3e0f3b..d20468744d5a4ad6e91566a91c89ecf93b5d4265 100644
--- a/ash/mus/bridge/shell_port_mash.h
+++ b/ash/mus/bridge/shell_port_mash.h
@@ -72,6 +72,8 @@ class ShellPortMash : public ShellPort, public WindowTreeHostManager::Observer {
   bool IsInUnifiedModeIgnoreMirroring() const override;
   void SetDisplayWorkAreaInsets(WmWindow* window,
                                 const gfx::Insets& insets) override;
+  std::unique_ptr<display::TouchTransformSetter> CreateTouchTransformDelegate()
+      override;
   void LockCursor() override;
   void UnlockCursor() override;
   void ShowCursor() override;