Add tests for InputDeviceServer/InputDeviceClient.

services/ui/input_devices/input_device_server.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "services/ui/input_devices/input_device_server.h"
 
 #include <utility>
 #include <vector>
 
 #include "mojo/public/cpp/bindings/array.h"
@@ skipping 16 matching lines @@
     manager_ = ui::DeviceDataManager::GetInstance();
     manager_->AddObserver(this);
   }
 }
 
 bool InputDeviceServer::IsRegisteredAsObserver() const {
   return manager_ != nullptr;
 }
 
 void InputDeviceServer::AddInterface(shell::Connection* connection) {
-  DCHECK(manager_);
+  DCHECK(IsRegisteredAsObserver());
   connection->AddInterface<mojom::InputDeviceServer>(this);
 }
 
 void InputDeviceServer::AddObserver(
     mojom::InputDeviceObserverMojoPtr observer) {
   // We only want to send this message once, so we need to check to make sure
   // device lists are actually complete before sending it to a new observer.
   if (manager_->AreDeviceListsComplete())
     SendDeviceListsComplete(observer.get());
   observers_.AddPtr(std::move(observer));
@@ skipping 53 matching lines @@
       manager_->GetKeyboardDevices(), manager_->GetTouchscreenDevices(),
       manager_->GetMouseDevices(), manager_->GetTouchpadDevices());
 }
 
 void InputDeviceServer::Create(const shell::Identity& remote_identity,
                                mojom::InputDeviceServerRequest request) {
   bindings_.AddBinding(this, std::move(request));
 }
 
 }  // namespace ui