Move device/core files to device/base directory.

device/core/device_client.cc

-// Copyright 2014 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 "device/core/device_client.h"
-
-#include "base/logging.h"
-
-namespace device {
-
-namespace {
-
-DeviceClient* g_instance;
-
-}  // namespace
-
-DeviceClient::DeviceClient() {
-  g_instance = this;
-}
-
-DeviceClient::~DeviceClient() {
-  g_instance = nullptr;
-}
-
-/* static */
-DeviceClient* DeviceClient::Get() {
-  DCHECK(g_instance);
-  return g_instance;
-}
-
-UsbService* DeviceClient::GetUsbService() {
-  // This should never be called by clients which do not support the USB API.
-  NOTREACHED();
-  return nullptr;
-}
-
-HidService* DeviceClient::GetHidService() {
-  // This should never be called by clients which do not support the HID API.
-  NOTREACHED();
-  return nullptr;
-}
-
-}  // namespace device