[scheduler] Add WakeupBudgetPool.

third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h

Index: third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h b/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
index 53b4514b39fc780e67c4c0e56518ece97b41fa16..afc28f6b24d5fa218dbbc47150270dfb80a98c78 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h
@@ -18,6 +18,8 @@ class BLINK_PLATFORM_EXPORT ThrottledTimeDomain : public RealTimeDomain {
   ThrottledTimeDomain(const char* tracing_category);
   ~ThrottledTimeDomain() override;
 
+  void SetNextTask(base::TimeTicks run_time);
+
   // TimeDomain implementation:
   const char* GetName() const override;
   void RequestWakeUpAt(base::TimeTicks now, base::TimeTicks run_time) override;
@@ -27,6 +29,10 @@ class BLINK_PLATFORM_EXPORT ThrottledTimeDomain : public RealTimeDomain {
   using TimeDomain::WakeUpReadyDelayedQueues;
 
  private:
+  // Next task run time provided by task queue throttler. Note that it does not
+  // get reset, so it is valid only when in the future.
+  base::Optional<base::TimeTicks> next_task_;
+
   DISALLOW_COPY_AND_ASSIGN(ThrottledTimeDomain);
 };