Add Mojo IPC based input-device service.

ui/views/mus/window_manager_connection.cc

Index: ui/views/mus/window_manager_connection.cc
diff --git a/ui/views/mus/window_manager_connection.cc b/ui/views/mus/window_manager_connection.cc
index f17c0aa96379af0e4f4211482041711d4505c760..a01f373cc9f40db51ba4a1d16b8fa5be244ec961 100644
--- a/ui/views/mus/window_manager_connection.cc
+++ b/ui/views/mus/window_manager_connection.cc
@@ -13,6 +13,7 @@
 #include "components/mus/public/cpp/window_property.h"
 #include "components/mus/public/cpp/window_tree_client.h"
 #include "components/mus/public/interfaces/event_matcher.mojom.h"
+#include "components/mus/public/interfaces/input_devices/input_devices.mojom.h"
 #include "components/mus/public/interfaces/window_tree.mojom.h"
 #include "services/shell/public/cpp/connection.h"
 #include "services/shell/public/cpp/connector.h"
@@ -114,13 +115,10 @@ WindowManagerConnection::WindowManagerConnection(
   screen_.reset(new ScreenMus(this));
   screen_->Init(connector);
 
-  if (!ui::DeviceDataManager::HasInstance()) {
-    // TODO(sad): We should have a DeviceDataManager implementation that talks
-    // to a mojo service to learn about the input-devices on the system.
-    // http://crbug.com/601981
-    ui::DeviceDataManager::CreateInstance();
-    created_device_data_manager_ = true;
-  }
+  // Receives updates about input-devices from other another process.
+  input_device::mojom::InputDeviceServerPtr service;
+  connector->ConnectToInterface("mojo:mus", &service);
+  input_device_client_.Connect(std::move(service));
 
   ViewsDelegate::GetInstance()->set_native_widget_factory(base::Bind(
       &WindowManagerConnection::CreateNativeWidgetMus,
@@ -132,8 +130,6 @@ WindowManagerConnection::~WindowManagerConnection() {
   // ~WindowTreeClient calls back to us (we're its delegate), destroy it while
   // we are still valid.
   client_.reset();
-  if (created_device_data_manager_)
-    ui::DeviceDataManager::DeleteInstance();
 
   if (ViewsDelegate::GetInstance()) {
     ViewsDelegate::GetInstance()->set_native_widget_factory(