Add frame rate flexibility token

Add support for temporarily relaxing frame rate restrictions in surface
flinger. This is used by CTS tests to get a consistent device state
while running frame rate tests.

Bug: 148033900

Test: - On a Pixel 4, I turned the brightness down and covered the
ambient light sensor, causing the display manager to set a frame rate
restriction. I ran the frame rate CTS test without these CLs applied,
and confirmed the test failed because surface flinger couldn't switch
frame rates, as expected. Then I ran the tests with the CLs applied, and
confirmed the tests pass.

- I confirmed that, without adopting shell permission identity, the CTS
test is denied the request to acquire a frame rate flexibility token. So
normal apps won't be able to access this.

Change-Id: Ie2b611cf5726c14a7a22e315a85bf6200d190682

api/test-current.txt

@@ -4820,6 +4820,11 @@ package android.view {
     method public abstract String asyncImpl() default "";
   }
 
+  public final class SurfaceControl implements android.os.Parcelable {
+    method public static long acquireFrameRateFlexibilityToken();
+    method public static void releaseFrameRateFlexibilityToken(long);
+  }
+
   public class SurfaceControlViewHost {
     method public void relayout(android.view.WindowManager.LayoutParams);
     method public void setView(@NonNull android.view.View, @NonNull android.view.WindowManager.LayoutParams);

core/java/android/view/SurfaceControl.java

@@ -32,6 +32,7 @@ import android.annotation.IntRange;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.Size;
+import android.annotation.TestApi;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.graphics.Bitmap;
 import android.graphics.ColorSpace;
@@ -216,6 +217,9 @@ public final class SurfaceControl implements Parcelable {
     private static native void nativeSetFrameRate(
             long transactionObj, long nativeObject, float frameRate, int compatibility);
 
+    private static native long nativeAcquireFrameRateFlexibilityToken();
+    private static native void nativeReleaseFrameRateFlexibilityToken(long token);
+
     private final CloseGuard mCloseGuard = CloseGuard.get();
     private String mName;
     /**
@@ -2868,4 +2872,24 @@ public final class SurfaceControl implements Parcelable {
             }
         }
     }
+
+    /**
+     * Acquire a frame rate flexibility token, which allows surface flinger to freely switch display
+     * frame rates. This is used by CTS tests to put the device in a consistent state. See
+     * ISurfaceComposer::acquireFrameRateFlexibilityToken().
+     * @hide
+     */
+    @TestApi
+    public static long acquireFrameRateFlexibilityToken() {
+        return nativeAcquireFrameRateFlexibilityToken();
+    }
+
+    /**
+     * Release a frame rate flexibility token.
+     * @hide
+     */
+    @TestApi
+    public static void releaseFrameRateFlexibilityToken(long token) {
+        nativeReleaseFrameRateFlexibilityToken(token);
+    }
 }

core/jni/android_view_SurfaceControl.cpp

@@ -29,11 +29,13 @@
 #include <android_runtime/AndroidRuntime.h>
 #include <android_runtime/android_view_Surface.h>
 #include <android_runtime/android_view_SurfaceSession.h>
+#include <gui/ISurfaceComposer.h>
 #include <gui/Surface.h>
 #include <gui/SurfaceComposerClient.h>
 #include <jni.h>
 #include <nativehelper/JNIHelp.h>
 #include <nativehelper/ScopedUtfChars.h>
+#include <private/gui/ComposerService.h>
 #include <stdio.h>
 #include <system/graphics.h>
 #include <ui/ConfigStoreTypes.h>
@@ -624,6 +626,23 @@ static void nativeSetFrameRate(JNIEnv* env, jclass clazz, jlong transactionObj,
     transaction->setFrameRate(ctrl, frameRate, static_cast<int8_t>(compatibility));
 }
 
+static jlong nativeAcquireFrameRateFlexibilityToken(JNIEnv* env, jclass clazz) {
+    sp<ISurfaceComposer> composer = ComposerService::getComposerService();
+    sp<IBinder> token;
+    status_t result = composer->acquireFrameRateFlexibilityToken(&token);
+    if (result < 0) {
+        ALOGE("Failed acquiring frame rate flexibility token: %s (%d)", strerror(-result), result);
+        return 0;
+    }
+    token->incStrong((void*)nativeAcquireFrameRateFlexibilityToken);
+    return reinterpret_cast<jlong>(token.get());
+}
+
+static void nativeReleaseFrameRateFlexibilityToken(JNIEnv* env, jclass clazz, jlong tokenLong) {
+    sp<IBinder> token(reinterpret_cast<IBinder*>(tokenLong));
+    token->decStrong((void*)nativeAcquireFrameRateFlexibilityToken);
+}
+
 static jlongArray nativeGetPhysicalDisplayIds(JNIEnv* env, jclass clazz) {
     const auto displayIds = SurfaceComposerClient::getPhysicalDisplayIds();
     jlongArray array = env->NewLongArray(displayIds.size());
@@ -1474,6 +1493,10 @@ static const JNINativeMethod sSurfaceControlMethods[] = {
             (void*)nativeSetShadowRadius },
     {"nativeSetFrameRate", "(JJFI)V",
             (void*)nativeSetFrameRate },
+    {"nativeAcquireFrameRateFlexibilityToken", "()J",
+            (void*)nativeAcquireFrameRateFlexibilityToken },
+    {"nativeReleaseFrameRateFlexibilityToken", "(J)V",
+            (void*)nativeReleaseFrameRateFlexibilityToken },
     {"nativeGetPhysicalDisplayIds", "()[J",
             (void*)nativeGetPhysicalDisplayIds },
     {"nativeGetPhysicalDisplayToken", "(J)Landroid/os/IBinder;",