Fix condition to register TabletModeChangeListeners

Should be empty check instead of null check. The bug was
introduced when it's moved over from InputManager
ag/21849880

Bug: 357504418
Test: m && presubmit
Flag: EXEMPT bugfix

Change-Id: Id900ab21d6ddb21d0251de418c76b2e81d2989c0

1 files changed, 1 insertions, 1 deletions

diff --git a/core/java/android/hardware/input/InputManagerGlobal.java b/core/java/android/hardware/input/InputManagerGlobal.java
index 03cf7c5f926c..2a362381a003 100644
--- a/core/java/android/hardware/input/InputManagerGlobal.java
+++ b/core/java/android/hardware/input/InputManagerGlobal.java
@@ -567,7 +567,7 @@ public final class InputManagerGlobal {
         Objects.requireNonNull(listener, "listener must not be null");
 
         synchronized (mOnTabletModeChangedListeners) {
-            if (mOnTabletModeChangedListeners == null) {
+            if (mOnTabletModeChangedListeners.isEmpty()) {
                 initializeTabletModeListenerLocked();
             }
             int idx = findOnTabletModeChangedListenerLocked(listener);