Fix potential NPE in NotificationRecord's KeyguardManager call

Fix: 288118117
Test: manual
Change-Id: I42396c914ee38f00dd122492ba332c095bbfd817

services/core/java/com/android/server/notification/NotificationRecord.java

@@ -103,7 +103,7 @@ public final class NotificationRecord {
     final int mTargetSdkVersion;
     final int mOriginalFlags;
     private final Context mContext;
-    private final KeyguardManager mKeyguardManager;
+    private KeyguardManager mKeyguardManager;
     private final PowerManager mPowerManager;
     NotificationUsageStats.SingleNotificationStats stats;
     boolean isCanceled;
@@ -1625,10 +1625,21 @@ public final class NotificationRecord {
     }
 
     boolean isLocked() {
-        return mKeyguardManager.isKeyguardLocked()
+        return getKeyguardManager().isKeyguardLocked()
                 || !mPowerManager.isInteractive();  // Unlocked AOD
     }
 
+    /**
+     * For some early {@link NotificationRecord}, {@link KeyguardManager} can be {@code null} in
+     * the constructor. Retrieve it again if it is null.
+     */
+    private KeyguardManager getKeyguardManager() {
+        if (mKeyguardManager == null) {
+            mKeyguardManager = mContext.getSystemService(KeyguardManager.class);
+        }
+        return mKeyguardManager;
+    }
+
     @VisibleForTesting
     static final class Light {
         public final int color;