GpuVSyncProvider with unit test

gpu/ipc/service/gpu_vsync_provider_unittest_win.cc

+// Copyright (c) 2016 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 "gpu/ipc/service/gpu_vsync_provider.h"
+
+#include <memory>
+
+#include "base/bind.h"
+#include "base/synchronization/lock.h"
+#include "base/synchronization/waitable_event.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/base/win/hidden_window.h"
+
+namespace gpu {
+
+class GpuVSyncProviderTest : public testing::Test {
+ public:
+  GpuVSyncProviderTest()
+      : vsync_event_(base::WaitableEvent::ResetPolicy::AUTOMATIC,
+                     base::WaitableEvent::InitialState::NOT_SIGNALED) {}
+  ~GpuVSyncProviderTest() override {}
+
+  void SetUp() override {}
+
+  void TearDown() override {}
+
+  void OnVSync(base::TimeTicks timestamp) {
+    // This is called on VSync worker thread.
+    base::AutoLock lock(lock_);
+    if (++vsync_count_ == 3)
+      vsync_event_.Signal();
+  }
+
+  int vsync_count() {
+    base::AutoLock lock(lock_);
+    return vsync_count_;
+  }
+
+  void reset_vsync_count() {
+    base::AutoLock lock(lock_);
+    vsync_count_ = 0;
+  }
+
+ protected:
+  base::WaitableEvent vsync_event_;
+
+ private:
+  base::Lock lock_;
+  int vsync_count_ = 0;
+};
+
+TEST_F(GpuVSyncProviderTest, VSyncSignalTest) {
+  SurfaceHandle window = ui::GetHiddenWindow();
+
+  std::unique_ptr<GpuVSyncProvider> provider = GpuVSyncProvider::Create(
+      base::Bind(&GpuVSyncProviderTest::OnVSync, base::Unretained(this)),
+      window);
+
+  constexpr base::TimeDelta wait_timeout =
+      base::TimeDelta::FromMilliseconds(300);
+
+  // Verify that there are no VSync signals before provider is enabled
+  bool wait_result = vsync_event_.TimedWait(wait_timeout);
+  EXPECT_FALSE(wait_result);
+  EXPECT_EQ(0, vsync_count());
+
+  provider->EnableVSync(true);
+
+  vsync_event_.Wait();
+
+  provider->EnableVSync(false);
+
+  // Verify that VSync callbacks stop coming after disabling.
+  // Please note that it might still be possible for one
+  // callback to be in flight on VSync worker thread, so |vsync_count_|
+  // could still be incremented once, but not enough times to trigger
+  // |vsync_event_|.
+  reset_vsync_count();
+  wait_result = vsync_event_.TimedWait(wait_timeout);
+  EXPECT_FALSE(wait_result);
+}
+
+}  // namespace gpu