Make ui::Compositor BeginFrame subscription robust

ui/compositor/compositor_unittest.cc

 // Copyright 2015 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 "base/run_loop.h"
 #include "base/thread_task_runner_handle.h"
 #include "cc/output/begin_frame_args.h"
 #include "cc/test/begin_frame_args_test.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/test/context_factories_for_test.h"
 #include "ui/compositor/test/draw_waiter_for_test.h"
 
 using testing::Mock;
 using testing::_;
 
 namespace ui {
 namespace {
 
+ACTION_P2(RemoveObserver, compositor, observer) {
+  compositor->RemoveBeginFrameObserver(observer);
+}
+
 class MockCompositorBeginFrameObserver : public CompositorBeginFrameObserver {
  public:
   MOCK_METHOD1(OnSendBeginFrame, void(const cc::BeginFrameArgs&));
 };
 
 // Test fixture for tests that require a ui::Compositor with a real task
 // runner.
 class CompositorTest : public testing::Test {
  public:
   CompositorTest() {}
@@ skipping 52 matching lines @@
     run_loop.Run();
     EXPECT_TRUE(compositor()->IsLocked());
   }
 }
 
 TEST_F(CompositorTest, AddAndRemoveBeginFrameObserver) {
   cc::BeginFrameArgs args =
     cc::CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE,
                                        base::TimeTicks::FromInternalValue(33));
 
-  // Simulate to trigger new BeginFrame by using |args|.
-  compositor()->SendBeginFramesToChildren(args);
+  MockCompositorBeginFrameObserver test_observer;
+  MockCompositorBeginFrameObserver test_observer2;
+
+  // Add a single observer.
+  compositor()->AddBeginFrameObserver(&test_observer);
+  Mock::VerifyAndClearExpectations(&test_observer);
 
   // When |missed_begin_frame_args_| is sent, its type is set to MISSED.
   cc::BeginFrameArgs expected_args(args);
-  expected_args.type = cc::BeginFrameArgs::MISSED;
+  cc::BeginFrameArgs expected_missed_args(args);
+  expected_missed_args.type = cc::BeginFrameArgs::MISSED;
 
-  MockCompositorBeginFrameObserver test_observer;
-  MockCompositorBeginFrameObserver test_observer2;
+  // Simulate to trigger new BeginFrame by using |args|.
   EXPECT_CALL(test_observer, OnSendBeginFrame(expected_args));
-  EXPECT_CALL(test_observer2, OnSendBeginFrame(expected_args));
+  compositor()->SendBeginFramesToChildren(args);
+  Mock::VerifyAndClearExpectations(&test_observer);
 
   // When new observer is added, Compositor immediately calls OnSendBeginFrame
   // with |missed_begin_frame_args_|.
-  compositor()->AddBeginFrameObserver(&test_observer);
+  EXPECT_CALL(test_observer2, OnSendBeginFrame(expected_missed_args));
   compositor()->AddBeginFrameObserver(&test_observer2);
   Mock::VerifyAndClearExpectations(&test_observer);
   Mock::VerifyAndClearExpectations(&test_observer2);
 
   // When |test_observer2| is removed and added again, it will be called again.
-  EXPECT_CALL(test_observer2, OnSendBeginFrame(expected_args));
+  EXPECT_CALL(test_observer2, OnSendBeginFrame(expected_missed_args));
   compositor()->RemoveBeginFrameObserver(&test_observer2);
   compositor()->AddBeginFrameObserver(&test_observer2);
   Mock::VerifyAndClearExpectations(&test_observer2);
 
   // When all observer is removed, |missed_begin_frame_args_| is invalidated.
   // So, it is not used for newly added observer.
   EXPECT_CALL(test_observer2, OnSendBeginFrame(_)).Times(0);
   compositor()->RemoveBeginFrameObserver(&test_observer);
   compositor()->RemoveBeginFrameObserver(&test_observer2);
+  compositor()->SendBeginFramesToChildren(args);
   compositor()->AddBeginFrameObserver(&test_observer2);
   Mock::VerifyAndClearExpectations(&test_observer2);
 
   compositor()->RemoveBeginFrameObserver(&test_observer2);
 }
 
+TEST_F(CompositorTest, RemoveBeginFrameObserverWhileSendingBeginFrame) {
+  cc::BeginFrameArgs args = cc::CreateBeginFrameArgsForTesting(
+      BEGINFRAME_FROM_HERE, base::TimeTicks::FromInternalValue(33));
+
+  cc::BeginFrameArgs expected_args(args);
+  cc::BeginFrameArgs expected_missed_args(args);
+  expected_missed_args.type = cc::BeginFrameArgs::MISSED;
+
+  // Add both observers, and simulate removal of |test_observer2| during
+  // BeginFrame dispatch (implicitly triggered when the observer is added).
+  MockCompositorBeginFrameObserver test_observer;
+  MockCompositorBeginFrameObserver test_observer2;
+  EXPECT_CALL(test_observer, OnSendBeginFrame(expected_args));
+  EXPECT_CALL(test_observer2, OnSendBeginFrame(expected_missed_args))
+      .WillOnce(RemoveObserver(compositor(), &test_observer2));
+
+  // When a new observer is added, Compositor immediately calls OnSendBeginFrame
+  // with |missed_begin_frame_args_|.
+  compositor()->AddBeginFrameObserver(&test_observer);
+  compositor()->SendBeginFramesToChildren(args);
+  compositor()->AddBeginFrameObserver(&test_observer2);
+  Mock::VerifyAndClearExpectations(&test_observer);
+  Mock::VerifyAndClearExpectations(&test_observer2);
+
+  // |test_observer2| was removed during the previous implicit BeginFrame
+  // dispatch, and should not get the new frame.
+  expected_args.type = cc::BeginFrameArgs::NORMAL;
+  EXPECT_CALL(test_observer, OnSendBeginFrame(expected_args));
+  EXPECT_CALL(test_observer2, OnSendBeginFrame(_)).Times(0);
+  compositor()->SendBeginFramesToChildren(args);
+  Mock::VerifyAndClearExpectations(&test_observer);
+  Mock::VerifyAndClearExpectations(&test_observer2);
+
+  // Now remove |test_observer| during explicit BeginFrame dispatch.
+  EXPECT_CALL(test_observer, OnSendBeginFrame(expected_args))
+      .WillOnce(RemoveObserver(compositor(), &test_observer));
+  EXPECT_CALL(test_observer2, OnSendBeginFrame(_)).Times(0);
+  compositor()->SendBeginFramesToChildren(args);
+  Mock::VerifyAndClearExpectations(&test_observer);
+  Mock::VerifyAndClearExpectations(&test_observer2);
+
+  // No observers should get the new frame.
+  EXPECT_CALL(test_observer, OnSendBeginFrame(_)).Times(0);
+  EXPECT_CALL(test_observer2, OnSendBeginFrame(_)).Times(0);
+  compositor()->SendBeginFramesToChildren(args);
+  Mock::VerifyAndClearExpectations(&test_observer);
+  Mock::VerifyAndClearExpectations(&test_observer2);
+
+  // Adding a new observer should not trigger a missed frame, as the
+  // previous frame had no observers.
+  EXPECT_CALL(test_observer, OnSendBeginFrame(_)).Times(0);
+  compositor()->AddBeginFrameObserver(&test_observer);
+  compositor()->RemoveBeginFrameObserver(&test_observer);
+  Mock::VerifyAndClearExpectations(&test_observer);
+}
+
 TEST_F(CompositorTest, ReleaseWidgetWithOutputSurfaceNeverCreated) {
   compositor()->SetVisible(false);
   EXPECT_EQ(gfx::kNullAcceleratedWidget,
             compositor()->ReleaseAcceleratedWidget());
   compositor()->SetAcceleratedWidget(gfx::kNullAcceleratedWidget);
   compositor()->SetVisible(true);
 }
 
 TEST_F(CompositorTest, CreateAndReleaseOutputSurface) {
   scoped_ptr<Layer> root_layer(new Layer(ui::LAYER_SOLID_COLOR));
   root_layer->SetBounds(gfx::Rect(10, 10));
   compositor()->SetRootLayer(root_layer.get());
   compositor()->SetScaleAndSize(1.0f, gfx::Size(10, 10));
   DCHECK(compositor()->IsVisible());
   compositor()->ScheduleDraw();
   DrawWaiterForTest::WaitForCompositingEnded(compositor());
   compositor()->SetVisible(false);
   EXPECT_EQ(gfx::kNullAcceleratedWidget,
             compositor()->ReleaseAcceleratedWidget());
   compositor()->SetAcceleratedWidget(gfx::kNullAcceleratedWidget);
   compositor()->SetVisible(true);
   compositor()->ScheduleDraw();
   DrawWaiterForTest::WaitForCompositingEnded(compositor());
   compositor()->SetRootLayer(nullptr);
 }
 
 }  // namespace ui