Add method to get current vsync from sf directly.

Bug: 205721584
Test: atest libsurfaceflinger_unittest
Test: atest DisplayEventReceiverTest
Change-Id: I38d4bd20bc2f2ad7ff964c3d613c28919478c0fc
diff --git a/services/surfaceflinger/tests/DisplayEventReceiver_test.cpp b/services/surfaceflinger/tests/DisplayEventReceiver_test.cpp
new file mode 100644
index 0000000..01adbc8
--- /dev/null
+++ b/services/surfaceflinger/tests/DisplayEventReceiver_test.cpp
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+#include <gui/DisplayEventReceiver.h>
+
+namespace android {
+
+class DisplayEventReceiverTest : public ::testing::Test {
+public:
+    void SetUp() override { EXPECT_EQ(NO_ERROR, mDisplayEventReceiver.initCheck()); }
+
+    DisplayEventReceiver mDisplayEventReceiver;
+};
+
+TEST_F(DisplayEventReceiverTest, getLatestVsyncEventData) {
+    const nsecs_t now = systemTime();
+    VsyncEventData vsyncEventData;
+    EXPECT_EQ(NO_ERROR, mDisplayEventReceiver.getLatestVsyncEventData(&vsyncEventData));
+
+    EXPECT_NE(std::numeric_limits<size_t>::max(), vsyncEventData.preferredFrameTimelineIndex);
+    EXPECT_GT(vsyncEventData.frameTimelines[0].deadlineTimestamp, now)
+            << "Deadline timestamp should be greater than frame time";
+    for (size_t i = 0; i < vsyncEventData.frameTimelines.size(); i++) {
+        EXPECT_NE(FrameTimelineInfo::INVALID_VSYNC_ID, vsyncEventData.frameTimelines[i].id);
+        EXPECT_GT(vsyncEventData.frameTimelines[i].expectedPresentTime,
+                  vsyncEventData.frameTimelines[i].deadlineTimestamp)
+                << "Expected vsync timestamp should be greater than deadline";
+        if (i > 0) {
+            EXPECT_GT(vsyncEventData.frameTimelines[i].deadlineTimestamp,
+                      vsyncEventData.frameTimelines[i - 1].deadlineTimestamp)
+                    << "Deadline timestamp out of order for frame timeline " << i;
+            EXPECT_GT(vsyncEventData.frameTimelines[i].expectedPresentTime,
+                      vsyncEventData.frameTimelines[i - 1].expectedPresentTime)
+                    << "Expected vsync timestamp out of order for frame timeline " << i;
+        }
+    }
+}
+
+} // namespace android
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