Add BeginFrameObserverProxy

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/test/test_simple_task_runner.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/test/context_factories_for_test.h"
 
+using testing::Mock;
+using testing::_;
+
 namespace ui {
 namespace {
 
+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() {}
   ~CompositorTest() override {}
 
   void SetUp() override {
     task_runner_ = new base::TestSimpleTaskRunner;
 
@@ skipping 31 matching lines @@
   EXPECT_FALSE(compositor()->IsLocked());
 
   // Ensure that the lock does not time out when set.
   compositor()->SetLocksWillTimeOut(false);
   lock = compositor()->GetCompositorLock();
   EXPECT_TRUE(compositor()->IsLocked());
   task_runner()->RunUntilIdle();
   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);
+
+  // When |missed_begin_frame_args_| is sent, its type is set to MISSED.
+  cc::BeginFrameArgs expected_args(args);
+  expected_args.type = cc::BeginFrameArgs::MISSED;
+
+  MockCompositorBeginFrameObserver test_observer;
+  EXPECT_CALL(test_observer, OnSendBeginFrame(expected_args));
+  // When new observer is added, Compositor immediately calls OnSendBeginFrame
+  // with |missed_begin_frame_args_|.
+  compositor()->AddBeginFrameObserver(&test_observer);
+  Mock::VerifyAndClearExpectations(&test_observer);
+
+  // |missed_begin_frame_args_| should be invalidated.
+  compositor()->RemoveBeginFrameObserver(&test_observer);
+  EXPECT_FALSE(compositor()->MissedBeginFrameArgsForTesting().IsValid());

[danakj, 2015/03/20 16:46:11]

This is testing internal implementation details still. I think what you want to
test is that:

If you add 2 observers, and remove one, then add it back, it gets called with
the last args.

If you remove both observers, then add one back, it does not get called with the
last args.

Ya?

[simonhong, 2015/03/20 17:24:14]

Yep, Thanks!

+}
+
 }  // namespace ui