Move throttling of background timers into the renderer scheduler

components/scheduler/renderer/throttling_helper.h

Index: components/scheduler/renderer/throttling_helper.h
diff --git a/components/scheduler/renderer/throttling_helper.h b/components/scheduler/renderer/throttling_helper.h
new file mode 100644
index 0000000000000000000000000000000000000000..8417d532d1c20bdbf3f04b847ba5b8152edbbf0e
--- /dev/null
+++ b/components/scheduler/renderer/throttling_helper.h
@@ -0,0 +1,61 @@
+// 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_RENDERER_THROTTLING_HELPER_H_
+#define COMPONENTS_SCHEDULER_RENDERER_THROTTLING_HELPER_H_
+
+#include <set>
+
+#include "base/macros.h"
+#include "components/scheduler/base/time_domain.h"
+#include "components/scheduler/scheduler_export.h"
+#include "third_party/WebKit/public/platform/WebViewScheduler.h"
+
+namespace scheduler {
+
+class RendererSchedulerImpl;
+class VirtualTimeDomain;
+class WebFrameSchedulerImpl;
+
+class SCHEDULER_EXPORT ThrottlingHelper : public TimeDomain::Observer {
+ public:
+  ThrottlingHelper(RendererSchedulerImpl* renderer_scheduler,
+                   const char* tracing_category);
+
+  ~ThrottlingHelper() override;
+
+  // TimeDomain::Observer implementation:
+  void OnTimeDomainHasImmediateWork() override;
+  void OnTimeDomainHasDelayedWork() override;
+
+  void Throttle(TaskQueue* task_queue);
+  void Unthrottle(TaskQueue* task_queue);
+
+  const VirtualTimeDomain* time_domain() const { return time_domain_.get(); }
+
+  static base::TimeDelta DelayToNextRunTimeInSeconds(base::TimeTicks now);
+
+ private:
+  void PumpThrottledTasks();
+  void MaybeSchedulePumpThrottledTasksLocked();
+
+  std::set<TaskQueue*> throttled_queues_;
+  base::Closure pump_throttled_tasks_closure_;
+  base::Closure forward_immediate_work_closure_;
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  RendererSchedulerImpl* renderer_scheduler_;  // NOT OWNED
+  base::TickClock* tick_clock_;                // NOT OWNED
+  const char* tracing_category_;               // NOT OWNED
+  scoped_ptr<VirtualTimeDomain> time_domain_;
+
+  bool pending_pump_throttled_tasks_;
+
+  base::WeakPtrFactory<ThrottlingHelper> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThrottlingHelper);
+};
+
+}  // namespace scheduler
+
+#endif  // COMPONENTS_SCHEDULER_RENDERER_THROTTLING_HELPER_H_