Add BeginFrameObserverProxy

ui/compositor/compositor_unittest.cc

Index: ui/compositor/compositor_unittest.cc
diff --git a/ui/compositor/compositor_unittest.cc b/ui/compositor/compositor_unittest.cc
index 810f1c96d0875938de0b2460aaddcb4eaf4568f4..781745d809afd2a80ba133b701498a54a026e558 100644
--- a/ui/compositor/compositor_unittest.cc
+++ b/ui/compositor/compositor_unittest.cc
@@ -3,13 +3,24 @@
 // 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 {
@@ -61,4 +72,28 @@ TEST_F(CompositorTest, LocksTimeOut) {
   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