Device Service: Decouple Wake Lock from //content

device/wake_lock/public/interfaces/wake_lock_service_context.mojom

+// Copyright 2015 The Chromium Authors. All rights reserved.

[Ken Rockot(use gerrit already), 2017/03/10 16:23:25]

2017

[blundell, 2017/03/15 11:06:11]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module device.mojom;
+
+import "device/wake_lock/public/interfaces/wake_lock_service.mojom";
+
+interface WakeLockServiceContext {

[Ken Rockot(use gerrit already), 2017/03/10 16:23:25]

If we're going to do this, as discussed offline I'd add a separate acquisition
interface so that a WakeLockContext pipe is always bound to a context ID:

interface WakeLockContextProvider {
  GetContext(int32 context_id, WakeLockContext& context);
}

interface WakeLockContext {
  GetWakeLock(WakeLock& wake_lock);

  HasWakeLockForTests() => (bool result);  // Also... Maybe [Sync]?
};

** I have omitted "Service" from all these names because we should also do that.

[blundell, 2017/03/15 11:06:11]

Done.
I initially made it Sync, but was scared off by all the comments here:
https://cs.chromium.org/chromium/src/mojo/public/cpp/bindings/sync_call_restr....
As it works fine async, there didn't seem to be a "very compelling reason" here.
I did that for the new interface. I didn't do it for the existing ones to avoid
adding churn to this CL; instead I filed crbug.com/701414 to follow up once the
dust settles here.

+  SetContextID(int32 context_id);
+  BindWakeLock(WakeLockService& wake_lock);
+  HasWakeLockForTests() => (bool result);
+};