Add GetWakeLockWithoutContext() in WakeLockContextProvider mojo interface.

device/wake_lock/wake_lock_service_context.h

 // 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.
 
 #ifndef DEVICE_WAKE_LOCK_WAKE_LOCK_SERVICE_CONTEXT_H_
 #define DEVICE_WAKE_LOCK_WAKE_LOCK_SERVICE_CONTEXT_H_
 
 #include <memory>
 #include <utility>
 
@@ skipping 18 matching lines @@
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
       const WakeLockContextCallback& native_view_getter);
   ~WakeLockServiceContext() override;
 
   // mojom::WakeLockContext:
   void GetWakeLock(mojom::WakeLockType type,
                    mojom::WakeLockReason reason,
                    const std::string& description,
                    mojom::WakeLockServiceRequest request) override;
 
+  static const int WakeLockInvalidContextId;
+
  private:
   scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
   int context_id_;
   WakeLockContextCallback native_view_getter_;
 
   DISALLOW_COPY_AND_ASSIGN(WakeLockServiceContext);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_WAKE_LOCK_WAKE_LOCK_SERVICE_CONTEXT_H_