Add log when upfps overlay isn't in sync with KeyguardUpdateMonitor

Log a debug msg when UdfpsController hides the udfps overlay when
KeyguardUpdateMonitor thinks that fingerprint is running. If we
get to this log, we expect a KeyguardUpdateMonitor fingerprintRunningState
update to 0 shortly afterwards. If not, there's a discrepancy between
UdfpsController and KeyguardUpdateMonitor which can lead to a bad state.
For example: the udfps icon not showing, but KeyguardUpdateMonitor thinks
that it's showing so UDFPS will not be re-requested.

Test: manual
Fixes: 197167446
Change-Id: I4cc97ae0fcc2f11a320fdcd014fbcf14227a011c

packages/SystemUI/src/com/android/systemui/biometrics/UdfpsController.java

@@ -256,6 +256,13 @@ public class UdfpsController implements DozeReceiver {
         @Override
         public void hideUdfpsOverlay(int sensorId) {
             mFgExecutor.execute(() -> {
+                if (mKeyguardUpdateMonitor.isFingerprintDetectionRunning()) {
+                    // if we get here, we expect keyguardUpdateMonitor's fingerprintRunningState
+                    // to be updated shortly afterwards
+                    Log.d(TAG, "hiding udfps overlay when "
+                            + "mKeyguardUpdateMonitor.isFingerprintDetectionRunning()=true");
+                }
+
                 mServerRequest = null;
                 updateOverlay();
             });