Experimental 'purging and suspending' backgrounded tabs behind the flag

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 <utility>
 
 #include "base/callback.h"
 #include "base/macros.h"
@@ skipping 2039 matching lines @@
   scheduler_->ResumeTimerQueue();
   RunUntilIdle();
   EXPECT_TRUE(run_order.empty());
 
   scheduler_->ResumeTimerQueue();
   RunUntilIdle();
   EXPECT_THAT(run_order,
               testing::ElementsAre(std::string("T1"), std::string("T2")));
 }
 
+TEST_F(RendererSchedulerImplTest, SuspendRendererWhenBackgrounded) {
+  // Assume that the renderer is backgrounded.
+  scheduler_->OnRendererBackgrounded();
+
+  // Tasks don't fire when the renderer is suspended.
+  std::vector<std::string> run_order;
+  PostTestTasks(&run_order, "T1 T2");
+  scheduler_->SuspendRendererWhenBackgrounded();
+  RunUntilIdle();
+  EXPECT_TRUE(run_order.empty());
+
+  // The queued tasks fire when the tab goes foregrounded.
+  scheduler_->OnRendererForegrounded();
+  RunUntilIdle();
+  EXPECT_THAT(run_order,
+              testing::ElementsAre(std::string("T1"), std::string("T2")));
+
+  // Even if the renderer is foregrounded when trying to suspend it, the
+  // renderer is not suspended.
+  run_order.clear();
+  PostTestTasks(&run_order, "T3 T4");
+  scheduler_->SuspendRendererWhenBackgrounded();
+  RunUntilIdle();
+  EXPECT_THAT(run_order,
+              testing::ElementsAre(std::string("T3"), std::string("T4")));
+}
+
 TEST_F(RendererSchedulerImplTest, UseCaseToString) {
   CheckAllUseCaseToString();
 }
 
 TEST_F(RendererSchedulerImplTest, MismatchedDidHandleInputEventOnMainThread) {
   // This should not DCHECK because there was no corresponding compositor side
   // call to DidHandleInputEventOnCompositorThread with
   // INPUT_EVENT_ACK_STATE_NOT_CONSUMED. There are legitimate reasons for the
   // compositor to not be there and we don't want to make debugging impossible.
   scheduler_->DidHandleInputEventOnMainThread(
@@ skipping 813 matching lines @@
   }
 
   // Timer tasks should not have been starved by the expensive compositor
   // tasks.
   EXPECT_EQ(TaskQueue::NORMAL_PRIORITY,
             scheduler_->CompositorTaskRunner()->GetQueuePriority());
   EXPECT_EQ(1000u, run_order.size());
 }
 
 }  // namespace scheduler