Prevent re-entrant calls to onPause

This can occur when launching an occluding activity where the user has
user the password bouncer. The IME animation begins, but is then
canceled in favor of the activity being launched, which begins a chain
of events that start a second call to pause.

Fixes: 236348317
Test: manual (follow steps in bug to launch occluding activity)
Change-Id: I158504872d41c96f1f6f27cab481945cd11c27e0

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

@@ -59,6 +59,7 @@ public class KeyguardPasswordViewController
     private final boolean mShowImeAtScreenOn;
     private EditText mPasswordEntry;
     private ImageView mSwitchImeButton;
+    private boolean mPaused;
 
     private final OnEditorActionListener mOnEditorActionListener = (v, actionId, event) -> {
         // Check if this was the result of hitting the enter key
@@ -202,6 +203,7 @@ public class KeyguardPasswordViewController
     @Override
     public void onResume(int reason) {
         super.onResume(reason);
+        mPaused = false;
         if (reason != KeyguardSecurityView.SCREEN_ON || mShowImeAtScreenOn) {
             showInput();
         }
@@ -222,6 +224,11 @@ public class KeyguardPasswordViewController
 
     @Override
     public void onPause() {
+        if (mPaused) {
+            return;
+        }
+        mPaused = true;
+
         if (!mPasswordEntry.isVisibleToUser()) {
             // Reset all states directly and then hide IME when the screen turned off.
             super.onPause();