Add GetWakeLockWithoutContext() in WakeLockContextProvider mojo interface.

device/wake_lock/wake_lock_service_context.cc

 // Copyright 2015 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/wake_lock/wake_lock_service_context.h"
 
 #include <utility>
 
 #include "device/wake_lock/wake_lock_service_impl.h"
 
 namespace device {
 
+const int WakeLockServiceContext::WakeLockInvalidContextId = -1;
+
 WakeLockServiceContext::WakeLockServiceContext(
     int context_id,
     scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
     const WakeLockContextCallback& native_view_getter)
     : file_task_runner_(std::move(file_task_runner)),
       context_id_(context_id),
       native_view_getter_(native_view_getter) {}
 
 WakeLockServiceContext::~WakeLockServiceContext() {}
 
 void WakeLockServiceContext::GetWakeLock(
     mojom::WakeLockType type,
     mojom::WakeLockReason reason,
     const std::string& description,
     mojom::WakeLockServiceRequest request) {
   // WakeLockServiceImpl owns itself.
   new WakeLockServiceImpl(std::move(request), type, reason, description,
                           context_id_, native_view_getter_, file_task_runner_);
 }
 
 }  // namespace device