scheduler: Don't block expensive loading tasks during main thread gestures

components/scheduler/renderer/renderer_scheduler_impl_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/scheduler/renderer/renderer_scheduler_impl.h"
 
 #include "base/callback.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "cc/output/begin_frame_args.h"
 #include "cc/test/ordered_simple_task_runner.h"
@@ skipping 2132 matching lines @@
   RunUntilIdle();
 
   EXPECT_EQ(RendererScheduler::UseCase::NONE, CurrentUseCase());
   EXPECT_TRUE(HaveSeenABeginMainframe());
   EXPECT_TRUE(LoadingTasksSeemExpensive());
   EXPECT_FALSE(TimerTasksSeemExpensive());
   EXPECT_TRUE(TouchStartExpectedSoon());
   EXPECT_THAT(run_order, testing::ElementsAre(std::string("D1")));
 }
 
+TEST_F(RendererSchedulerImplTest,
+       ExpensiveLoadingTasksNotBlockedDuringMainThreadGestures) {
+  std::vector<std::string> run_order;
+
+  SimulateExpensiveTasks(loading_task_runner_);
+
+  // Loading tasks should not be disabled during main thread user user
+  // interactions.
+  PostTestTasks(&run_order, "C1 L1");
+
+  // Trigger main_thread_gesture UseCase
+  WillBeginMainThreadGestureFrame();
+  RunUntilIdle();
+  EXPECT_EQ(RendererScheduler::UseCase::MAIN_THREAD_GESTURE, CurrentUseCase());
+
+  EXPECT_TRUE(LoadingTasksSeemExpensive());
+  EXPECT_FALSE(TimerTasksSeemExpensive());
+  EXPECT_THAT(run_order,
+              testing::ElementsAre(std::string("C1"), std::string("L1")));
+}
+
 TEST_F(RendererSchedulerImplTest, ModeratelyExpensiveTimer_NotBlocked) {
   scheduler_->SetHasVisibleRenderWidgetWithTouchHandler(true);
   for (int i = 0; i < 20; i++) {
     simulate_timer_task_ran_ = false;
     compositor_task_runner_->PostTask(
         FROM_HERE,
         base::Bind(
             &RendererSchedulerImplTest::SimulateMainThreadGestureCompositorTask,
             base::Unretained(this), base::TimeDelta::FromMilliseconds(4)));
     timer_task_runner_->PostTask(
@@ skipping 42 matching lines @@
     }
 
     base::TimeDelta time_till_next_frame =
         EstimatedNextFrameBegin() - clock_->NowTicks();
     if (time_till_next_frame > base::TimeDelta())
       clock_->Advance(time_till_next_frame);
   }
 }
 
 }  // namespace scheduler