Experimental 'purging and suspending' backgrounded tabs behind the flag

components/scheduler/renderer/renderer_scheduler_impl_unittest.cc

Index: components/scheduler/renderer/renderer_scheduler_impl_unittest.cc
diff --git a/components/scheduler/renderer/renderer_scheduler_impl_unittest.cc b/components/scheduler/renderer/renderer_scheduler_impl_unittest.cc
index 1a8944443ae6c699d3cef55ec96911ca2136af1f..fad2902ad0923cfed32e31d7a73cd7d835500e6a 100644
--- a/components/scheduler/renderer/renderer_scheduler_impl_unittest.cc
+++ b/components/scheduler/renderer/renderer_scheduler_impl_unittest.cc
@@ -2057,6 +2057,33 @@ TEST_F(RendererSchedulerImplTest, MultipleSuspendsNeedMultipleResumes) {
               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();
 }