diff --git a/services/core/java/com/android/server/app/GameManagerService.java b/services/core/java/com/android/server/app/GameManagerService.java
index d195103..893c8b5 100644
--- a/services/core/java/com/android/server/app/GameManagerService.java
+++ b/services/core/java/com/android/server/app/GameManagerService.java
@@ -40,6 +40,7 @@
 import android.app.GameState;
 import android.app.IGameManagerService;
 import android.app.IGameModeListener;
+import android.app.IUidObserver;
 import android.app.StatsManager;
 import android.content.BroadcastReceiver;
 import android.content.Context;
@@ -165,38 +166,19 @@
     private final ArrayMap<IGameModeListener, Integer> mGameModeListeners = new ArrayMap<>();
     @Nullable
     private final GameServiceController mGameServiceController;
+    private final Object mUidObserverLock = new Object();
+    @VisibleForTesting
+    @Nullable
+    final UidObserver mUidObserver;
+    @GuardedBy("mUidObserverLock")
+    private final Set<Integer> mForegroundGameUids = new HashSet<>();
 
     public GameManagerService(Context context) {
         this(context, createServiceThread().getLooper());
     }
 
     GameManagerService(Context context, Looper looper) {
-        mContext = context;
-        mHandler = new SettingsHandler(looper);
-        mPackageManager = mContext.getPackageManager();
-        mUserManager = mContext.getSystemService(UserManager.class);
-        mPowerManagerInternal = LocalServices.getService(PowerManagerInternal.class);
-        mSystemDir = new File(Environment.getDataDirectory(), "system");
-        mSystemDir.mkdirs();
-        FileUtils.setPermissions(mSystemDir.toString(),
-                FileUtils.S_IRWXU | FileUtils.S_IRWXG | FileUtils.S_IROTH | FileUtils.S_IXOTH,
-                -1, -1);
-        mGameModeInterventionListFile = new AtomicFile(new File(mSystemDir,
-                                                     GAME_MODE_INTERVENTION_LIST_FILE_NAME));
-        FileUtils.setPermissions(mGameModeInterventionListFile.getBaseFile().getAbsolutePath(),
-                FileUtils.S_IRUSR | FileUtils.S_IWUSR
-                        | FileUtils.S_IRGRP | FileUtils.S_IWGRP,
-                -1, -1);
-        if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_GAME_SERVICE)) {
-            mGameServiceController = new GameServiceController(
-                    context, BackgroundThread.getExecutor(),
-                    new GameServiceProviderSelectorImpl(
-                            context.getResources(),
-                            context.getPackageManager()),
-                    new GameServiceProviderInstanceFactoryImpl(context));
-        } else {
-            mGameServiceController = null;
-        }
+        this(context, looper, Environment.getDataDirectory());
     }
 
     @VisibleForTesting(visibility = VisibleForTesting.Visibility.PRIVATE)
@@ -227,6 +209,14 @@
         } else {
             mGameServiceController = null;
         }
+        mUidObserver = new UidObserver();
+        try {
+            ActivityManager.getService().registerUidObserver(mUidObserver,
+                    ActivityManager.UID_OBSERVER_PROCSTATE | ActivityManager.UID_OBSERVER_GONE,
+                    ActivityManager.PROCESS_STATE_UNKNOWN, null);
+        } catch (RemoteException e) {
+            Slog.w(TAG, "Could not register UidObserver");
+        }
     }
 
     @Override
@@ -2152,4 +2142,66 @@
      * load dynamic library for frame rate overriding JNI calls
      */
     private static native void nativeSetOverrideFrameRate(int uid, float frameRate);
+
+    final class UidObserver extends IUidObserver.Stub {
+        @Override
+        public void onUidIdle(int uid, boolean disabled) {}
+
+        @Override
+        public void onUidGone(int uid, boolean disabled) {
+            synchronized (mUidObserverLock) {
+                disableGameMode(uid);
+            }
+        }
+
+        @Override
+        public void onUidActive(int uid) {}
+
+        @Override
+        public void onUidStateChanged(int uid, int procState, long procStateSeq, int capability) {
+            synchronized (mUidObserverLock) {
+                if (ActivityManager.isProcStateBackground(procState)) {
+                    disableGameMode(uid);
+                    return;
+                }
+
+                final String[] packages = mContext.getPackageManager().getPackagesForUid(uid);
+                if (packages == null || packages.length == 0) {
+                    return;
+                }
+
+                final int userId = mContext.getUserId();
+                if (!Arrays.stream(packages).anyMatch(p -> isPackageGame(p, userId))) {
+                    return;
+                }
+
+                if (mForegroundGameUids.isEmpty()) {
+                    Slog.v(TAG, "Game power mode ON (process state was changed to foreground)");
+                    mPowerManagerInternal.setPowerMode(Mode.GAME, true);
+                }
+                mForegroundGameUids.add(uid);
+            }
+        }
+
+        private void disableGameMode(int uid) {
+            synchronized (mUidObserverLock) {
+                if (!mForegroundGameUids.contains(uid)) {
+                    return;
+                }
+                mForegroundGameUids.remove(uid);
+                if (!mForegroundGameUids.isEmpty()) {
+                    return;
+                }
+                Slog.v(TAG,
+                        "Game power mode OFF (process remomved or state changed to background)");
+                mPowerManagerInternal.setPowerMode(Mode.GAME, false);
+            }
+        }
+
+        @Override
+        public void onUidCachedChanged(int uid, boolean cached) {}
+
+        @Override
+        public void onUidProcAdjChanged(int uid) {}
+    }
 }
diff --git a/services/tests/mockingservicestests/AndroidManifest.xml b/services/tests/mockingservicestests/AndroidManifest.xml
index 33ac735..ea0481e 100644
--- a/services/tests/mockingservicestests/AndroidManifest.xml
+++ b/services/tests/mockingservicestests/AndroidManifest.xml
@@ -43,6 +43,9 @@
     <!-- needed by TrustManagerServiceTest to access LockSettings' secure storage -->
     <uses-permission android:name="android.permission.ACCESS_KEYGUARD_SECURE_STORAGE" />
 
+    <!-- needed by GameManagerServiceTest because GameManager creates a UidObserver -->
+    <uses-permission android:name="android.permission.PACKAGE_USAGE_STATS" />
+
     <application android:testOnly="true"
                  android:debuggable="true">
         <uses-library android:name="android.test.runner" />
diff --git a/services/tests/mockingservicestests/src/com/android/server/app/GameManagerServiceTests.java b/services/tests/mockingservicestests/src/com/android/server/app/GameManagerServiceTests.java
index c4c50424..32243f0 100644
--- a/services/tests/mockingservicestests/src/com/android/server/app/GameManagerServiceTests.java
+++ b/services/tests/mockingservicestests/src/com/android/server/app/GameManagerServiceTests.java
@@ -36,6 +36,7 @@
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.eq;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.reset;
@@ -45,6 +46,7 @@
 
 import android.Manifest;
 import android.annotation.Nullable;
+import android.app.ActivityManager;
 import android.app.GameManager;
 import android.app.GameModeConfiguration;
 import android.app.GameModeInfo;
@@ -2212,4 +2214,106 @@
         assertEquals(expectedInterventionListOutput,
                 gameManagerService.getInterventionList(mPackageName, USER_ID_1));
     }
+
+    @Test
+    public void testGamePowerMode_gamePackage() throws Exception {
+        GameManagerService gameManagerService = createServiceAndStartUser(USER_ID_1);
+        String[] packages = {mPackageName};
+        when(mMockPackageManager.getPackagesForUid(DEFAULT_PACKAGE_UID)).thenReturn(packages);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        verify(mMockPowerManager, times(1)).setPowerMode(Mode.GAME, true);
+    }
+
+    @Test
+    public void testGamePowerMode_twoGames() throws Exception {
+        GameManagerService gameManagerService = createServiceAndStartUser(USER_ID_1);
+        String[] packages1 = {mPackageName};
+        when(mMockPackageManager.getPackagesForUid(DEFAULT_PACKAGE_UID)).thenReturn(packages1);
+        String someGamePkg = "some.game";
+        String[] packages2 = {someGamePkg};
+        int somePackageId = DEFAULT_PACKAGE_UID + 1;
+        when(mMockPackageManager.getPackagesForUid(somePackageId)).thenReturn(packages2);
+        HashMap<Integer, Boolean> powerState = new HashMap<>();
+        doAnswer(inv -> powerState.put(inv.getArgument(0), inv.getArgument(1)))
+                .when(mMockPowerManager).setPowerMode(anyInt(), anyBoolean());
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        assertTrue(powerState.get(Mode.GAME));
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_TRANSIENT_BACKGROUND, 0, 0);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                somePackageId, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        assertTrue(powerState.get(Mode.GAME));
+        gameManagerService.mUidObserver.onUidStateChanged(
+                somePackageId, ActivityManager.PROCESS_STATE_TRANSIENT_BACKGROUND, 0, 0);
+        assertFalse(powerState.get(Mode.GAME));
+    }
+
+    @Test
+    public void testGamePowerMode_twoGamesOverlap() throws Exception {
+        GameManagerService gameManagerService = createServiceAndStartUser(USER_ID_1);
+        String[] packages1 = {mPackageName};
+        when(mMockPackageManager.getPackagesForUid(DEFAULT_PACKAGE_UID)).thenReturn(packages1);
+        String someGamePkg = "some.game";
+        String[] packages2 = {someGamePkg};
+        int somePackageId = DEFAULT_PACKAGE_UID + 1;
+        when(mMockPackageManager.getPackagesForUid(somePackageId)).thenReturn(packages2);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                somePackageId, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_TRANSIENT_BACKGROUND, 0, 0);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                somePackageId, ActivityManager.PROCESS_STATE_TRANSIENT_BACKGROUND, 0, 0);
+        verify(mMockPowerManager, times(1)).setPowerMode(Mode.GAME, true);
+        verify(mMockPowerManager, times(1)).setPowerMode(Mode.GAME, false);
+    }
+
+    @Test
+    public void testGamePowerMode_released() throws Exception {
+        GameManagerService gameManagerService = createServiceAndStartUser(USER_ID_1);
+        String[] packages = {mPackageName};
+        when(mMockPackageManager.getPackagesForUid(DEFAULT_PACKAGE_UID)).thenReturn(packages);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_TRANSIENT_BACKGROUND, 0, 0);
+        verify(mMockPowerManager, times(1)).setPowerMode(Mode.GAME, false);
+    }
+
+    @Test
+    public void testGamePowerMode_noPackage() throws Exception {
+        GameManagerService gameManagerService = createServiceAndStartUser(USER_ID_1);
+        String[] packages = {};
+        when(mMockPackageManager.getPackagesForUid(DEFAULT_PACKAGE_UID)).thenReturn(packages);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        verify(mMockPowerManager, times(0)).setPowerMode(Mode.GAME, true);
+    }
+
+    @Test
+    public void testGamePowerMode_notAGamePackage() throws Exception {
+        mockAppCategory(mPackageName, ApplicationInfo.CATEGORY_IMAGE);
+        GameManagerService gameManagerService = createServiceAndStartUser(USER_ID_1);
+        String[] packages = {"someapp"};
+        when(mMockPackageManager.getPackagesForUid(DEFAULT_PACKAGE_UID)).thenReturn(packages);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        verify(mMockPowerManager, times(0)).setPowerMode(Mode.GAME, true);
+    }
+
+    @Test
+    public void testGamePowerMode_notAGamePackageNotReleased() throws Exception {
+        mockAppCategory(mPackageName, ApplicationInfo.CATEGORY_IMAGE);
+        GameManagerService gameManagerService = createServiceAndStartUser(USER_ID_1);
+        String[] packages = {"someapp"};
+        when(mMockPackageManager.getPackagesForUid(DEFAULT_PACKAGE_UID)).thenReturn(packages);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_FOREGROUND_SERVICE, 0, 0);
+        gameManagerService.mUidObserver.onUidStateChanged(
+                DEFAULT_PACKAGE_UID, ActivityManager.PROCESS_STATE_TRANSIENT_BACKGROUND, 0, 0);
+        verify(mMockPowerManager, times(0)).setPowerMode(Mode.GAME, false);
+    }
 }