(reland) Adds TimeDomains to the TaskQueueManager

components/scheduler/base/virtual_time_domain.h

Index: components/scheduler/base/virtual_time_domain.h
diff --git a/components/scheduler/base/virtual_time_domain.h b/components/scheduler/base/virtual_time_domain.h
new file mode 100644
index 0000000000000000000000000000000000000000..2e384144d4c20918ca08cb3ffeb1c4bc6a080389
--- /dev/null
+++ b/components/scheduler/base/virtual_time_domain.h
@@ -0,0 +1,45 @@
+// 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 COMPONENTS_SCHEDULER_BASE_VIRTUAL_TIME_DOMAIN_H_
+#define COMPONENTS_SCHEDULER_BASE_VIRTUAL_TIME_DOMAIN_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "components/scheduler/base/time_domain.h"
+#include "components/scheduler/scheduler_export.h"
+
+namespace scheduler {
+class TaskQueueManagerDelegate;
+
+class SCHEDULER_EXPORT VirtualTimeDomain : public TimeDomain {
+ public:
+  VirtualTimeDomain(base::TimeTicks initial_time);
+
+  // TimeDomain implementation:
+  LazyNow CreateLazyNow() override;
+  bool MaybeAdvanceTime() override;
+  const char* GetName() const override;
+
+  // Advances this time domain to |now|. NOTE |now| is supposed to be
+  // monotonically increasing.
+  void AdvanceTo(base::TimeTicks now);
+
+ protected:
+  void RequestWakeup(base::TimeDelta delay) override;
+  void AsValueIntoInternal(
+      base::trace_event::TracedValue* state) const override;
+
+ private:
+  mutable base::Lock lock_;  // Protects |now_|.
+  base::TimeTicks now_;
+
+  ~VirtualTimeDomain() override;
+
+  DISALLOW_COPY_AND_ASSIGN(VirtualTimeDomain);
+};
+
+}  // namespace scheduler
+
+#endif  // COMPONENTS_SCHEDULER_BASE_VIRTUAL_TIME_DOMAIN_H_