Add Mojo IPC based input-device service.

components/mus/mus_app.h

Index: components/mus/mus_app.h
diff --git a/components/mus/mus_app.h b/components/mus/mus_app.h
index 3a5285f91b37c6a2123567e9ecd5ef09abb54d7d..794744842db47e256a46cdfd90f79c3712919e76 100644
--- a/components/mus/mus_app.h
+++ b/components/mus/mus_app.h
@@ -7,12 +7,14 @@
 
 #include <stdint.h>
 
+#include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "components/mus/input_devices/input_device_server.h"
 #include "components/mus/public/interfaces/clipboard.mojom.h"
 #include "components/mus/public/interfaces/display.mojom.h"
 #include "components/mus/public/interfaces/gpu.mojom.h"
@@ -150,6 +152,8 @@ class MusApp
 
   UserIdToUserState user_id_to_user_state_;
 
+  input_device::InputDeviceServer input_device_server_;
+
   bool test_config_;
   bool use_chrome_gpu_command_buffer_;
 #if defined(USE_OZONE)