Run task queue manager work in batches

content/renderer/scheduler/renderer_scheduler_impl.cc

Index: content/renderer/scheduler/renderer_scheduler_impl.cc
diff --git a/content/renderer/scheduler/renderer_scheduler_impl.cc b/content/renderer/scheduler/renderer_scheduler_impl.cc
index a0f683f95888f1a0fa9a8809cbaddfa0800e7017..d66269b0a69b0b3cb0f6d2798642c3981963b35e 100644
--- a/content/renderer/scheduler/renderer_scheduler_impl.cc
+++ b/content/renderer/scheduler/renderer_scheduler_impl.cc
@@ -43,6 +43,8 @@ RendererSchedulerImpl::RendererSchedulerImpl(
       CONTROL_TASK_QUEUE, RendererTaskQueueSelector::CONTROL_PRIORITY);
   renderer_task_queue_selector_->DisableQueue(IDLE_TASK_QUEUE);
   task_queue_manager_->SetAutoPump(IDLE_TASK_QUEUE, false);
+  // See crbug.com/444764 for how this work batch size was derived.
+  task_queue_manager_->SetWorkBatchSize(4);
 
   for (size_t i = 0; i < TASK_QUEUE_COUNT; i++) {
     task_queue_manager_->SetQueueName(
@@ -239,8 +241,15 @@ void RendererSchedulerImpl::EndIdlePeriod() {
   renderer_task_queue_selector_->DisableQueue(IDLE_TASK_QUEUE);
 }
 
+void RendererSchedulerImpl::SetTimeSourceForTesting(
+    scoped_refptr<cc::TestNowSource> time_source) {
+  main_thread_checker_.CalledOnValidThread();
+  time_source_ = time_source;
+  task_queue_manager_->SetTimeSourceForTesting(time_source);
+}
+
 base::TimeTicks RendererSchedulerImpl::Now() const {
-  return gfx::FrameTime::Now();
+  return UNLIKELY(time_source_) ? time_source_->Now() : base::TimeTicks::Now();
 }
 
 RendererSchedulerImpl::PollableNeedsUpdateFlag::PollableNeedsUpdateFlag(