diff --git a/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp b/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp
index 8e7440c..9a962bc 100644
--- a/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp
+++ b/services/surfaceflinger/tests/unittests/LayerHistoryTest.cpp
@@ -1,140 +1,243 @@
 #undef LOG_TAG
-#define LOG_TAG "LayerHistoryUnittests"
+#define LOG_TAG "LayerHistoryTest"
 
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
-
 #include <log/log.h>
 
-#include <mutex>
-#include <thread>
-
 #include "Scheduler/LayerHistory.h"
+#include "Scheduler/LayerInfo.h"
+#include "TestableScheduler.h"
+#include "TestableSurfaceFlinger.h"
+#include "mock/MockLayer.h"
 
 using testing::_;
 using testing::Return;
 
-namespace android {
-namespace scheduler {
+namespace android::scheduler {
 
 class LayerHistoryTest : public testing::Test {
-public:
-    LayerHistoryTest();
-    ~LayerHistoryTest() override;
-
 protected:
-    std::unique_ptr<LayerHistory> mLayerHistory;
+    static constexpr auto PRESENT_TIME_HISTORY_SIZE = LayerInfo::PresentTimeHistory::HISTORY_SIZE;
+    static constexpr auto MAX_FREQUENT_LAYER_PERIOD_NS = LayerInfo::MAX_FREQUENT_LAYER_PERIOD_NS;
 
-    static constexpr float MIN_REFRESH_RATE = 30.f;
-    static constexpr float MAX_REFRESH_RATE = 90.f;
-    static constexpr auto RELEVANT_FRAME_THRESHOLD = 90u;
-    static constexpr uint64_t THIRTY_FPS_INTERVAL = 33'333'333;
+    static constexpr float LO_FPS = 30.f;
+    static constexpr nsecs_t LO_FPS_PERIOD = 33'333'333;
 
-    void forceRelevancy(const std::unique_ptr<LayerHistory::LayerHandle>& testLayer) {
-        mLayerHistory->setVisibility(testLayer, true);
-        for (auto i = 0u; i < RELEVANT_FRAME_THRESHOLD; i++) {
-            mLayerHistory->insert(testLayer, 0, false /*isHDR*/);
-        }
-    };
-};
+    static constexpr float HI_FPS = 90.f;
+    static constexpr nsecs_t HI_FPS_PERIOD = 11'111'111;
 
-LayerHistoryTest::LayerHistoryTest() {
-    mLayerHistory = std::make_unique<LayerHistory>();
-}
-LayerHistoryTest::~LayerHistoryTest() {}
+    LayerHistoryTest() { mFlinger.resetScheduler(mScheduler); }
 
-namespace {
-TEST_F(LayerHistoryTest, oneLayer) {
-    std::unique_ptr<LayerHistory::LayerHandle> testLayer =
-            mLayerHistory->createLayer("TestLayer", MIN_REFRESH_RATE, MAX_REFRESH_RATE);
-    mLayerHistory->setVisibility(testLayer, true);
-    for (auto i = 0u; i < RELEVANT_FRAME_THRESHOLD; i++) {
-        EXPECT_FLOAT_EQ(0.f, mLayerHistory->getDesiredRefreshRateAndHDR().first);
-        mLayerHistory->insert(testLayer, 0, false /*isHDR*/);
+    LayerHistory& history() { return mScheduler->mutableLayerHistory(); }
+    const LayerHistory& history() const { return mScheduler->mutableLayerHistory(); }
+
+    size_t layerCount() const NO_THREAD_SAFETY_ANALYSIS { return history().mLayerInfos.size(); }
+    size_t activeLayerCount() const NO_THREAD_SAFETY_ANALYSIS { return history().mActiveLayersEnd; }
+
+    size_t frequentLayerCount(nsecs_t now) const NO_THREAD_SAFETY_ANALYSIS {
+        const auto& infos = history().mLayerInfos;
+        return std::count_if(infos.begin(), infos.begin() + history().mActiveLayersEnd,
+                             [now](const auto& pair) { return pair.second->isFrequent(now); });
     }
 
-    // Add a few more. This time we should get MAX refresh rate as the layer
-    // becomes relevant
-    static constexpr auto A_FEW = 10;
-    for (auto i = 0u; i < A_FEW; i++) {
-        EXPECT_FLOAT_EQ(MAX_REFRESH_RATE, mLayerHistory->getDesiredRefreshRateAndHDR().first);
-        mLayerHistory->insert(testLayer, 0, false /*isHDR*/);
+    auto createLayer() { return sp<mock::MockLayer>(new mock::MockLayer(mFlinger.flinger())); }
+
+    RefreshRateConfigs mConfigs{true,
+                                {RefreshRateConfigs::InputConfig{0, LO_FPS_PERIOD},
+                                 RefreshRateConfigs::InputConfig{1, HI_FPS_PERIOD}},
+                                0};
+    TestableScheduler* const mScheduler{new TestableScheduler(mConfigs)};
+    TestableSurfaceFlinger mFlinger;
+
+    const nsecs_t mTime = systemTime();
+};
+
+namespace {
+
+TEST_F(LayerHistoryTest, oneLayer) {
+    const auto layer = createLayer();
+    constexpr bool isHDR = false;
+    EXPECT_CALL(*layer, isVisible()).WillRepeatedly(Return(true));
+
+    EXPECT_EQ(1, layerCount());
+    EXPECT_EQ(0, activeLayerCount());
+
+    // 0 FPS is returned if no layers are active.
+    EXPECT_FLOAT_EQ(0, history().summarize(mTime).maxRefreshRate);
+    EXPECT_EQ(0, activeLayerCount());
+
+    // 0 FPS is returned if active layers have insufficient history.
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE - 1; i++) {
+        history().record(layer.get(), 0, isHDR, mTime);
+        EXPECT_FLOAT_EQ(0, history().summarize(mTime).maxRefreshRate);
+        EXPECT_EQ(1, activeLayerCount());
+    }
+
+    // High FPS is returned once enough history has been recorded.
+    for (int i = 0; i < 10; i++) {
+        history().record(layer.get(), 0, isHDR, mTime);
+        EXPECT_FLOAT_EQ(HI_FPS, history().summarize(mTime).maxRefreshRate);
+        EXPECT_EQ(1, activeLayerCount());
     }
 }
 
 TEST_F(LayerHistoryTest, oneHDRLayer) {
-    std::unique_ptr<LayerHistory::LayerHandle> testLayer =
-            mLayerHistory->createLayer("TestHDRLayer", MIN_REFRESH_RATE, MAX_REFRESH_RATE);
-    mLayerHistory->setVisibility(testLayer, true);
+    const auto layer = createLayer();
+    constexpr bool isHDR = true;
+    EXPECT_CALL(*layer, isVisible()).WillRepeatedly(Return(true));
 
-    mLayerHistory->insert(testLayer, 0, true /*isHDR*/);
-    EXPECT_FLOAT_EQ(0.0f, mLayerHistory->getDesiredRefreshRateAndHDR().first);
-    EXPECT_EQ(true, mLayerHistory->getDesiredRefreshRateAndHDR().second);
+    EXPECT_EQ(1, layerCount());
+    EXPECT_EQ(0, activeLayerCount());
 
-    mLayerHistory->setVisibility(testLayer, false);
-    EXPECT_FLOAT_EQ(0.0f, mLayerHistory->getDesiredRefreshRateAndHDR().first);
-    EXPECT_EQ(false, mLayerHistory->getDesiredRefreshRateAndHDR().second);
+    history().record(layer.get(), 0, isHDR, mTime);
+    auto summary = history().summarize(mTime);
+    EXPECT_FLOAT_EQ(0, summary.maxRefreshRate);
+    EXPECT_TRUE(summary.isHDR);
+    EXPECT_EQ(1, activeLayerCount());
+
+    EXPECT_CALL(*layer, isVisible()).WillRepeatedly(Return(false));
+
+    summary = history().summarize(mTime);
+    EXPECT_FLOAT_EQ(0, summary.maxRefreshRate);
+    EXPECT_FALSE(summary.isHDR);
+    EXPECT_EQ(0, activeLayerCount());
 }
 
 TEST_F(LayerHistoryTest, explicitTimestamp) {
-    std::unique_ptr<LayerHistory::LayerHandle> test30FpsLayer =
-            mLayerHistory->createLayer("30FpsLayer", MIN_REFRESH_RATE, MAX_REFRESH_RATE);
-    mLayerHistory->setVisibility(test30FpsLayer, true);
+    const auto layer = createLayer();
+    constexpr bool isHDR = false;
+    EXPECT_CALL(*layer, isVisible()).WillRepeatedly(Return(true));
 
-    nsecs_t startTime = systemTime();
-    for (int i = 0; i < RELEVANT_FRAME_THRESHOLD; i++) {
-        mLayerHistory->insert(test30FpsLayer, startTime + (i * THIRTY_FPS_INTERVAL),
-                              false /*isHDR*/);
+    EXPECT_EQ(1, layerCount());
+    EXPECT_EQ(0, activeLayerCount());
+
+    nsecs_t time = mTime;
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE; i++) {
+        history().record(layer.get(), time, isHDR, time);
+        time += LO_FPS_PERIOD;
     }
 
-    EXPECT_FLOAT_EQ(30.f, mLayerHistory->getDesiredRefreshRateAndHDR().first);
+    EXPECT_FLOAT_EQ(LO_FPS, history().summarize(mTime).maxRefreshRate);
+    EXPECT_EQ(1, activeLayerCount());
+    EXPECT_EQ(1, frequentLayerCount(time));
 }
 
 TEST_F(LayerHistoryTest, multipleLayers) {
-    std::unique_ptr<LayerHistory::LayerHandle> testLayer =
-            mLayerHistory->createLayer("TestLayer", MIN_REFRESH_RATE, MAX_REFRESH_RATE);
-    mLayerHistory->setVisibility(testLayer, true);
-    std::unique_ptr<LayerHistory::LayerHandle> test30FpsLayer =
-            mLayerHistory->createLayer("30FpsLayer", MIN_REFRESH_RATE, MAX_REFRESH_RATE);
-    mLayerHistory->setVisibility(test30FpsLayer, true);
-    std::unique_ptr<LayerHistory::LayerHandle> testLayer2 =
-            mLayerHistory->createLayer("TestLayer2", MIN_REFRESH_RATE, MAX_REFRESH_RATE);
-    mLayerHistory->setVisibility(testLayer2, true);
+    auto layer1 = createLayer();
+    auto layer2 = createLayer();
+    auto layer3 = createLayer();
+    constexpr bool isHDR = false;
 
-    nsecs_t startTime = systemTime();
-    for (int i = 0; i < RELEVANT_FRAME_THRESHOLD; i++) {
-        mLayerHistory->insert(testLayer, 0, false /*isHDR*/);
+    EXPECT_CALL(*layer1, isVisible()).WillRepeatedly(Return(true));
+    EXPECT_CALL(*layer2, isVisible()).WillRepeatedly(Return(true));
+    EXPECT_CALL(*layer3, isVisible()).WillRepeatedly(Return(true));
+
+    nsecs_t time = mTime;
+
+    EXPECT_EQ(3, layerCount());
+    EXPECT_EQ(0, activeLayerCount());
+    EXPECT_EQ(0, frequentLayerCount(time));
+
+    // layer1 is active but infrequent.
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE; i++) {
+        history().record(layer1.get(), time, isHDR, time);
+        time += MAX_FREQUENT_LAYER_PERIOD_NS.count();
     }
-    EXPECT_FLOAT_EQ(MAX_REFRESH_RATE, mLayerHistory->getDesiredRefreshRateAndHDR().first);
 
-    startTime = systemTime();
-    for (int i = 0; i < RELEVANT_FRAME_THRESHOLD; i++) {
-        mLayerHistory->insert(test30FpsLayer, startTime + (i * THIRTY_FPS_INTERVAL),
-                              false /*isHDR*/);
+    EXPECT_FLOAT_EQ(LO_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(1, activeLayerCount());
+    EXPECT_EQ(0, frequentLayerCount(time));
+
+    // layer2 is frequent and has high refresh rate.
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE; i++) {
+        history().record(layer2.get(), time, isHDR, time);
+        time += HI_FPS_PERIOD;
     }
-    EXPECT_FLOAT_EQ(MAX_REFRESH_RATE, mLayerHistory->getDesiredRefreshRateAndHDR().first);
 
-    for (int i = 10; i < RELEVANT_FRAME_THRESHOLD; i++) {
-        mLayerHistory->insert(test30FpsLayer, startTime + (i * THIRTY_FPS_INTERVAL),
-                              false /*isHDR*/);
+    // layer1 is still active but infrequent.
+    history().record(layer1.get(), time, isHDR, time);
+
+    EXPECT_FLOAT_EQ(HI_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(2, activeLayerCount());
+    EXPECT_EQ(1, frequentLayerCount(time));
+
+    // layer1 is no longer active.
+    // layer2 is frequent and has low refresh rate.
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE; i++) {
+        history().record(layer2.get(), time, isHDR, time);
+        time += LO_FPS_PERIOD;
     }
-    EXPECT_FLOAT_EQ(MAX_REFRESH_RATE, mLayerHistory->getDesiredRefreshRateAndHDR().first);
 
-    // This frame is only around for 9 occurrences, so it doesn't throw
-    // anything off.
-    for (int i = 0; i < 9; i++) {
-        mLayerHistory->insert(testLayer2, 0, false /*isHDR*/);
+    EXPECT_FLOAT_EQ(LO_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(1, activeLayerCount());
+    EXPECT_EQ(1, frequentLayerCount(time));
+
+    // layer2 still has low refresh rate.
+    // layer3 has high refresh rate but not enough history.
+    constexpr int RATIO = LO_FPS_PERIOD / HI_FPS_PERIOD;
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE - 1; i++) {
+        if (i % RATIO == 0) {
+            history().record(layer2.get(), time, isHDR, time);
+        }
+
+        history().record(layer3.get(), time, isHDR, time);
+        time += HI_FPS_PERIOD;
     }
-    EXPECT_FLOAT_EQ(MAX_REFRESH_RATE, mLayerHistory->getDesiredRefreshRateAndHDR().first);
-    // After 1200 ms frames become obsolete.
-    std::this_thread::sleep_for(std::chrono::milliseconds(1500));
 
-    mLayerHistory->insert(test30FpsLayer,
-                          startTime + (RELEVANT_FRAME_THRESHOLD * THIRTY_FPS_INTERVAL),
-                          false /*isHDR*/);
-    EXPECT_FLOAT_EQ(30.f, mLayerHistory->getDesiredRefreshRateAndHDR().first);
+    EXPECT_FLOAT_EQ(LO_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(2, activeLayerCount());
+    EXPECT_EQ(2, frequentLayerCount(time));
+
+    // layer3 becomes recently active.
+    history().record(layer3.get(), time, isHDR, time);
+    EXPECT_FLOAT_EQ(HI_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(2, activeLayerCount());
+    EXPECT_EQ(2, frequentLayerCount(time));
+
+    // layer1 expires.
+    layer1.clear();
+    EXPECT_FLOAT_EQ(HI_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(2, layerCount());
+    EXPECT_EQ(2, activeLayerCount());
+    EXPECT_EQ(2, frequentLayerCount(time));
+
+    // layer2 still has low refresh rate.
+    // layer3 becomes inactive.
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE; i++) {
+        history().record(layer2.get(), time, isHDR, time);
+        time += LO_FPS_PERIOD;
+    }
+
+    EXPECT_FLOAT_EQ(LO_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(1, activeLayerCount());
+    EXPECT_EQ(1, frequentLayerCount(time));
+
+    // layer2 expires.
+    layer2.clear();
+    EXPECT_FLOAT_EQ(0, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(1, layerCount());
+    EXPECT_EQ(0, activeLayerCount());
+    EXPECT_EQ(0, frequentLayerCount(time));
+
+    // layer3 becomes active and has high refresh rate.
+    for (int i = 0; i < PRESENT_TIME_HISTORY_SIZE; i++) {
+        history().record(layer3.get(), time, isHDR, time);
+        time += HI_FPS_PERIOD;
+    }
+
+    EXPECT_FLOAT_EQ(HI_FPS, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(1, layerCount());
+    EXPECT_EQ(1, activeLayerCount());
+    EXPECT_EQ(1, frequentLayerCount(time));
+
+    // layer3 expires.
+    layer3.clear();
+    EXPECT_FLOAT_EQ(0, history().summarize(time).maxRefreshRate);
+    EXPECT_EQ(0, layerCount());
+    EXPECT_EQ(0, activeLayerCount());
+    EXPECT_EQ(0, frequentLayerCount(time));
 }
 
 } // namespace
-} // namespace scheduler
-} // namespace android
\ No newline at end of file
+} // namespace android::scheduler
diff --git a/services/surfaceflinger/tests/unittests/TestableScheduler.h b/services/surfaceflinger/tests/unittests/TestableScheduler.h
index ae72467..ae6aa89 100644
--- a/services/surfaceflinger/tests/unittests/TestableScheduler.h
+++ b/services/surfaceflinger/tests/unittests/TestableScheduler.h
@@ -48,6 +48,7 @@
     auto& mutableEventControlThread() { return mEventControlThread; }
     auto& mutablePrimaryDispSync() { return mPrimaryDispSync; }
     auto& mutableHWVsyncAvailable() { return mHWVsyncAvailable; }
+    auto& mutableLayerHistory() { return mLayerHistory; }
 
     ~TestableScheduler() {
         // All these pointer and container clears help ensure that GMock does
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index c7664fb..94fc5f7 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -22,6 +22,7 @@
 #include <compositionengine/OutputLayer.h>
 #include <compositionengine/impl/CompositionEngine.h>
 #include <compositionengine/impl/OutputLayerCompositionState.h>
+#include <compositionengine/mock/DisplaySurface.h>
 
 #include "BufferQueueLayer.h"
 #include "BufferStateLayer.h"
@@ -173,6 +174,7 @@
 
 class TestableSurfaceFlinger {
 public:
+    SurfaceFlinger* flinger() { return mFlinger.get(); }
     TestableScheduler* scheduler() { return mScheduler; }
 
     // Extend this as needed for accessing SurfaceFlinger private (and public)
@@ -207,13 +209,15 @@
 
         mFlinger->mAppConnectionHandle = mScheduler->createConnection(std::move(appEventThread));
         mFlinger->mSfConnectionHandle = mScheduler->createConnection(std::move(sfEventThread));
+        resetScheduler(mScheduler);
 
-        mFlinger->mScheduler.reset(mScheduler);
         mFlinger->mVSyncModulator.emplace(*mScheduler, mFlinger->mAppConnectionHandle,
                                           mFlinger->mSfConnectionHandle,
                                           mFlinger->mPhaseOffsets->getCurrentOffsets());
     }
 
+    void resetScheduler(Scheduler* scheduler) { mFlinger->mScheduler.reset(scheduler); }
+
     using CreateBufferQueueFunction = surfaceflinger::test::Factory::CreateBufferQueueFunction;
     void setCreateBufferQueueFunction(CreateBufferQueueFunction f) {
         mFactory.mCreateBufferQueue = f;
diff --git a/services/surfaceflinger/tests/unittests/mock/MockLayer.h b/services/surfaceflinger/tests/unittests/mock/MockLayer.h
new file mode 100644
index 0000000..f375e23
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/mock/MockLayer.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2019 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.
+ */
+
+#pragma once
+
+#include <gmock/gmock.h>
+
+#include "Layer.h"
+
+namespace android::mock {
+
+class MockLayer : public Layer {
+public:
+    explicit MockLayer(SurfaceFlinger* flinger)
+          : Layer(LayerCreationArgs(flinger, nullptr, "TestLayer", 800, 600, 0, {})) {}
+
+    MOCK_CONST_METHOD0(getType, const char*());
+    MOCK_CONST_METHOD0(isVisible, bool());
+    MOCK_METHOD0(createClone, sp<Layer>());
+};
+
+} // namespace android::mock