[scheduler] Implement time-based cpu throttling.

third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc

Index: third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
index 1b0980a4f4e00ccf236f4bc2250683d0b744c3b7..93f57591149c1ee42b42b627e9af42c3169550d9 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc
@@ -514,6 +514,11 @@ bool TaskQueueImpl::IsEmpty() const {
 }
 
 bool TaskQueueImpl::HasPendingImmediateWork() const {
+  LazyNow lazy_now = main_thread_only().time_domain->CreateLazyNow();
+  return HasPendingImmediateWork(&lazy_now);
+}
+
+bool TaskQueueImpl::HasPendingImmediateWork(LazyNow* lazy_now) const {
   // Any work queue tasks count as immediate work.
   if (!main_thread_only().delayed_work_queue->Empty() ||
       !main_thread_only().immediate_work_queue->Empty()) {
@@ -524,7 +529,7 @@ bool TaskQueueImpl::HasPendingImmediateWork() const {
   // immediate work.
   if (!main_thread_only().delayed_incoming_queue.empty() &&
       main_thread_only().delayed_incoming_queue.begin()->delayed_run_time <=
-          main_thread_only().time_domain->CreateLazyNow().Now()) {
+          lazy_now->Now()) {
     return true;
   }
 
@@ -533,6 +538,26 @@ bool TaskQueueImpl::HasPendingImmediateWork() const {
   return !any_thread().immediate_incoming_queue.empty();
 }
 
+base::Optional<base::TimeTicks> TaskQueueImpl::GetNextScheduledWakeUp() {
+  LazyNow lazy_now = main_thread_only().time_domain->CreateLazyNow();
+  MoveReadyDelayedTasksToDelayedWorkQueue(&lazy_now);
+
+  if (main_thread_only().delayed_incoming_queue.empty())
+    return base::nullopt;
+
+  return main_thread_only().delayed_incoming_queue.begin()->delayed_run_time;
+}
+
+base::Optional<base::TimeTicks> TaskQueueImpl::GetNextTaskRunTime() {
+  LazyNow lazy_now = main_thread_only().time_domain->CreateLazyNow();
+  MoveReadyDelayedTasksToDelayedWorkQueue(&lazy_now);
+
+  if (HasPendingImmediateWork())
+    return lazy_now.Now();
+
+  return GetNextScheduledWakeUp();
+}
+
 void TaskQueueImpl::MoveReadyDelayedTasksToDelayedWorkQueue(LazyNow* lazy_now) {
   // Enqueue all delayed tasks that should be running now.
   while (!main_thread_only().delayed_incoming_queue.empty()) {