[scheduler] Teach scheduler about audio state

third_party/WebKit/Source/platform/scheduler/base/delayed_switch.h

+// Copyright 2016 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 THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_DELAYED_SWITCH_H_
+#define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_DELAYED_SWITCH_H_
+
+#include "public/platform/WebCommon.h"
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "platform/scheduler/base/cancelable_closure_holder.h"
+
+namespace base {
+class TaskRunner;
+}
+
+namespace blink {
+namespace scheduler {
+
+// This class is designed to proxy calls to |Enable| and |Disable| and
+// delay call to |Disable| for |disable_delay| time.
+// It forwards calls to |enable_callback| and |disable_callback| accouting
+// for required delay.
+// NOTE: This class is main-thread only.
+class BLINK_PLATFORM_EXPORT DelayedSwitch {

[Sami, 2016/09/29 13:36:07]

bikeshed: DebouncedSwitch might be a more accurate name for this because the
enable isn't delayed.

[altimin, 2016/09/29 16:29:42]

Acknowledged.

+ public:
+  DelayedSwitch(
+      base::TaskRunner* task_runner,

[alex clarke (OOO till 29th), 2016/09/29 11:16:53]

Any particular reason for using base::TaskRunner instead of a TaskQueue?

[altimin, 2016/09/29 16:29:43]

Acknowledged.

+      base::TimeDelta disable_delay,
+      base::Closure enable_callback,
+      base::Closure disable_callback);
+  ~DelayedSwitch();
+
+  void Enable();

[alex clarke (OOO till 29th), 2016/09/29 11:16:53]

In some ways I like Enable/Disable but the the content/ layer has a bool as does
the TaskQueueThrottler.  Feels a little odd.

[altimin, 2016/09/29 16:29:43]

Done.

+
+  void Disable();
+
+  // Switch is disabled by default.
+  bool IsEnabled() const;
+
+ private:
+  enum class State {
+    ENABLED, DISABLED
+  };
+
+  void DoDisable();
+
+  State state_;
+
+  base::TaskRunner* task_runner_;  // NOT OWNED

[alex clarke (OOO till 29th), 2016/09/29 11:16:53]

This should be a scoped_refptr<>

[Sami, 2016/09/29 13:36:07]

+1, also pass it in as one in the constructor to make it clear ownership is
taken.

[altimin, 2016/09/29 16:29:42]

Acknowledged.

+
+  base::TimeDelta disable_delay_;
+
+  base::Closure enable_callback_;
+  base::Closure disable_callback_;
+
+  CancelableClosureHolder delayed_disable_task_;
+  bool has_disable_task_queued_;
+
+  base::WeakPtrFactory<DelayedSwitch> weak_ptr_factory_;
+};

[alex clarke (OOO till 29th), 2016/09/29 11:16:53]

DISALLOW_COPY_AND_ASSIGN(DelayedSwitch);

[altimin, 2016/09/29 16:29:42]

Acknowledged.

+
+}  // namespace scheduler
+}  // namespace blink
+
+#endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_DELAYED_SWITCH_H_
+