SurfaceFlinger: add Refresh Rate overlay

Add an overlay to indicate what is the current refresh rate.
Currently it is implemented by a ColorLayer:
 - Red - Default refresh rate
 - Green - Performance refresh rate

To enable the overlay:
adb shell service call SurfaceFlinger 1034 i32 1
To disable the overlay:
adb shell service call SurfaceFlinger 1034 i32 0

Test: manual
Change-Id: I851f2530e7accacd2cac446b30aa2e0b6d431a92
diff --git a/services/surfaceflinger/RefreshRateOverlay.cpp b/services/surfaceflinger/RefreshRateOverlay.cpp
new file mode 100644
index 0000000..e70bfe4
--- /dev/null
+++ b/services/surfaceflinger/RefreshRateOverlay.cpp
@@ -0,0 +1,53 @@
+/*
+ * 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.
+ */
+
+#include "RefreshRateOverlay.h"
+#include "Client.h"
+#include "Layer.h"
+
+namespace android {
+
+using RefreshRateType = scheduler::RefreshRateConfigs::RefreshRateType;
+
+RefreshRateOverlay::RefreshRateOverlay(SurfaceFlinger& flinger)
+      : mFlinger(flinger), mClient(new Client(&mFlinger)) {
+    createLayer();
+}
+
+bool RefreshRateOverlay::createLayer() {
+    const status_t ret =
+            mFlinger.createLayer(String8("RefreshRateOverlay"), mClient, 0, 0,
+                                 PIXEL_FORMAT_RGBA_8888, ISurfaceComposerClient::eFXSurfaceColor,
+                                 LayerMetadata(), &mIBinder, &mGbp, &mLayer);
+    if (ret) {
+        ALOGE("failed to color layer");
+        return false;
+    }
+
+    mLayer = mClient->getLayerUser(mIBinder);
+    mLayer->setCrop_legacy(Rect(0, 0, 200, 100), true);
+    mLayer->setLayer(INT32_MAX - 2);
+
+    return true;
+}
+
+void RefreshRateOverlay::changeRefreshRate(RefreshRateType type) {
+    const half3& color = (type == RefreshRateType::PERFORMANCE) ? GREEN : RED;
+    mLayer->setColor(color);
+    mFlinger.setTransactionFlags(eTransactionMask);
+}
+
+}; // namespace android