Issue scheduleWatchdog command on background thread

FaceManager/FingerprintManager#scheduleWatchdog commands do Binder IPC
in fire-and-forget manner. Move them to background thread to avoid
binder jank.

Bug: 279928682
Test: DeviceEntryFaceAuthRepository is covered by passing unit tests.
      Tested face auth change on a cheetah.
Change-Id: I8a0e6578dc871cbb5e08aef9250d174f79c4f765

packages/SystemUI/src/com/android/keyguard/KeyguardUpdateMonitor.java

@@ -4543,13 +4543,18 @@ public class KeyguardUpdateMonitor implements TrustManager.TrustListener, Dumpab
      * Cancels all operations in the scheduler if it is hung for 10 seconds.
      */
     public void startBiometricWatchdog() {
-        if (mFaceManager != null && !isFaceAuthInteractorEnabled()) {
-            mLogger.scheduleWatchdog("face");
-            mFaceManager.scheduleWatchdog();
-        }
-        if (mFpm != null) {
-            mLogger.scheduleWatchdog("fingerprint");
-            mFpm.scheduleWatchdog();
-        }
+        final boolean isFaceAuthInteractorEnabled = isFaceAuthInteractorEnabled();
+        mBackgroundExecutor.execute(() -> {
+            Trace.beginSection("#startBiometricWatchdog");
+            if (mFaceManager != null && !isFaceAuthInteractorEnabled) {
+                mLogger.scheduleWatchdog("face");
+                mFaceManager.scheduleWatchdog();
+            }
+            if (mFpm != null) {
+                mLogger.scheduleWatchdog("fingerprint");
+                mFpm.scheduleWatchdog();
+            }
+            Trace.endSection();
+        });
     }
 }

packages/SystemUI/src/com/android/systemui/keyguard/data/repository/DeviceEntryFaceAuthRepository.kt

@@ -31,6 +31,7 @@ import com.android.systemui.common.coroutine.ChannelExt.trySendWithFailureLoggin
 import com.android.systemui.common.coroutine.ConflatedCallbackFlow.conflatedCallbackFlow
 import com.android.systemui.dagger.SysUISingleton
 import com.android.systemui.dagger.qualifiers.Application
+import com.android.systemui.dagger.qualifiers.Background
 import com.android.systemui.dagger.qualifiers.Main
 import com.android.systemui.dump.DumpManager
 import com.android.systemui.flags.FeatureFlags
@@ -126,6 +127,7 @@ constructor(
     private val keyguardBypassController: KeyguardBypassController? = null,
     @Application private val applicationScope: CoroutineScope,
     @Main private val mainDispatcher: CoroutineDispatcher,
+    @Background private val backgroundDispatcher: CoroutineDispatcher,
     private val sessionTracker: SessionTracker,
     private val uiEventsLogger: UiEventLogger,
     private val faceAuthLogger: FaceAuthenticationLogger,
@@ -228,8 +230,12 @@ constructor(
         keyguardTransitionInteractor.anyStateToGoneTransition
             .filter { it.transitionState == TransitionState.FINISHED }
             .onEach {
-                faceAuthLogger.watchdogScheduled()
-                faceManager?.scheduleWatchdog()
+                // We deliberately want to run this in background because scheduleWatchdog does
+                // a Binder IPC.
+                withContext(backgroundDispatcher) {
+                    faceAuthLogger.watchdogScheduled()
+                    faceManager?.scheduleWatchdog()
+                }
             }
             .launchIn(applicationScope)
     }

packages/SystemUI/tests/src/com/android/systemui/keyguard/data/repository/DeviceEntryFaceAuthRepositoryTest.kt

@@ -228,6 +228,7 @@ class DeviceEntryFaceAuthRepositoryTest : SysuiTestCase() {
             bypassControllerOverride,
             testScope.backgroundScope,
             testDispatcher,
+            testDispatcher,
             sessionTracker,
             uiEventLogger,
             FaceAuthenticationLogger(logcatLogBuffer("DeviceEntryFaceAuthRepositoryLog")),