Fences should not be added to new queues when virtual time is disabled

Bug: 791742
Change-Id: Idc2e85972893dddf7ae62eefe5e99859f96e9a14
Reviewed-on: https://chromium-review.googlesource.com/970473
Commit-Queue: Alex Clarke <alexclarke@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544671}

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

@@ -702,9 +702,13 @@ scoped_refptr<MainThreadTaskQueue> RendererSchedulerImpl::NewTaskQueue(
   if (task_queue->CanBeThrottled())
     AddQueueToWakeUpBudgetPool(task_queue.get());
 
-  if (queue_class == MainThreadTaskQueue::QueueClass::kTimer) {
-    if (main_thread_only().virtual_time_stopped)
-      task_queue->InsertFence(TaskQueue::InsertFencePosition::kNow);
+  // If this is a timer queue, and virtual time is enabled and paused, it should
+  // be suspended by adding a fence to prevent immediate tasks from running when
+  // they're not supposed to.
+  if (queue_class == MainThreadTaskQueue::QueueClass::kTimer &&
+      main_thread_only().virtual_time_stopped &&
+      main_thread_only().use_virtual_time) {
+    task_queue->InsertFence(TaskQueue::InsertFencePosition::kNow);
   }
 
   return task_queue;

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl_unittest.cc

@@ -3729,6 +3729,15 @@ TEST_F(RendererSchedulerImplTest, UnthrottledTaskRunner) {
   EXPECT_EQ(500u, unthrottled_count);
 }
 
+TEST_F(RendererSchedulerImplTest,
+       VirtualTimePolicyDoesNotAffectNewTimerTaskQueueIfVirtualTimeNotEnabled) {
+  scheduler_->SetVirtualTimePolicy(
+      PageSchedulerImpl::VirtualTimePolicy::kPause);
+  scoped_refptr<MainThreadTaskQueue> timer_tq = scheduler_->NewTimerTaskQueue(
+      MainThreadTaskQueue::QueueType::kFrameThrottleable);
+  EXPECT_FALSE(timer_tq->HasActiveFence());
+}
+
 TEST_F(RendererSchedulerImplTest, EnableVirtualTime) {
   EXPECT_FALSE(scheduler_->IsVirtualTimeEnabled());
   scheduler_->EnableVirtualTime(