[scheduler] Implement time-based cpu throttling.

third_party/WebKit/public/platform/scheduler/base/task_queue.h

Index: third_party/WebKit/public/platform/scheduler/base/task_queue.h
diff --git a/third_party/WebKit/public/platform/scheduler/base/task_queue.h b/third_party/WebKit/public/platform/scheduler/base/task_queue.h
index 5612f6e90cde270760bb1b03a117a47a91949554..6572c35b52659f8ceb07acdb56a2e2286d5d19ca 100644
--- a/third_party/WebKit/public/platform/scheduler/base/task_queue.h
+++ b/third_party/WebKit/public/platform/scheduler/base/task_queue.h
@@ -7,7 +7,9 @@
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
+#include "base/optional.h"
 #include "base/single_thread_task_runner.h"
+#include "base/time/time.h"
 #include "public/platform/WebCommon.h"
 
 namespace base {
@@ -101,10 +103,15 @@ class BLINK_PLATFORM_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
   // Returns true if the queue is completely empty.
   virtual bool IsEmpty() const = 0;
 
-  // Returns true if the queue has work that's ready to execute now. NOTE this
-  // must be called on the thread this TaskQueue was created by.
+  // Returns true if the queue has work that's ready to execute now.
+  // NOTE: this must be called on the thread this TaskQueue was created by.
   virtual bool HasPendingImmediateWork() const = 0;
 
+  // Returns requested run time of next delayed task, which is not ready
+  // to run. If there are no such tasks, returns base::nullopt.
+  // NOTE: this must be called on the thread this TaskQueue was created by.
+  virtual base::Optional<base::TimeTicks> GetNextScheduledWakeUp() = 0;
+
   // Can be called on any thread.
   virtual const char* GetName() const = 0;