Add GetWakeLockWithoutContext() in WakeLockContextProvider mojo interface.

device/wake_lock/wake_lock_service_impl.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_impl.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 
@@ skipping 115 matching lines @@
   // mojom::WakeLockReason once all its clients are converted to be the clients
   // of WakeLock.
   wake_lock_ = base::MakeUnique<PowerSaveBlocker>(
       ToPowerSaveBlockerType(type_), ToPowerSaveBlockerReason(reason_),
       *description_, main_task_runner_, file_task_runner_);
 
   if (type_ != mojom::WakeLockType::PreventDisplaySleep)
     return;
 
 #if defined(OS_ANDROID)
+  if (context_id_ == WakeLockServiceContext::WakeLockInvalidContextId)
+    return;

[blundell, 2017/05/12 12:42:18]

Maybe we should LOG(ERROR) here, as if the client is using a wake lock to
prevent display sleep on Android and isn't passing a context ID, they're quite
likely not getting the behavior they want.

[ke.he, 2017/05/12 16:09:38]

Done.

+
   gfx::NativeView native_view = native_view_getter_.Run(context_id_);
   if (native_view)
     wake_lock_.get()->InitDisplaySleepBlocker(native_view);
 #endif
 }
 
 void WakeLockServiceImpl::RemoveWakeLock() {
   DCHECK(wake_lock_);
   wake_lock_.reset();
 }
 
 void WakeLockServiceImpl::OnConnectionError() {
   // If this client has an outstanding wake lock request, decrease the
   // num_lock_requests and call UpdateWakeLock().
   if (*binding_set_.dispatch_context() && num_lock_requests_ > 0) {
     num_lock_requests_--;
     UpdateWakeLock();
   }
 
   if (binding_set_.empty())
     base::ThreadTaskRunnerHandle::Get()->DeleteSoon(FROM_HERE, this);
 }
 
 }  // namespace device