Null out launcher reference to prevent leak

Bug: 314806687
Flag: None
Test: Enabled flag and played with taskbar/home transitions,
seemed fine

Change-Id: I86ab417eccf1fd6255195025890a1b93bf5d3bb4
diff --git a/quickstep/src/com/android/launcher3/HomeTransitionController.java b/quickstep/src/com/android/launcher3/HomeTransitionController.java
index b264115..2b50283 100644
--- a/quickstep/src/com/android/launcher3/HomeTransitionController.java
+++ b/quickstep/src/com/android/launcher3/HomeTransitionController.java
@@ -28,19 +28,16 @@
  */
 public class HomeTransitionController {
 
-    private final QuickstepLauncher mLauncher;
+    @Nullable private QuickstepLauncher mLauncher;
     @Nullable private IHomeTransitionListener mHomeTransitionListener;
 
-    public HomeTransitionController(QuickstepLauncher launcher) {
+    public void registerHomeTransitionListener(QuickstepLauncher launcher) {
         mLauncher = launcher;
-    }
-
-    public void registerHomeTransitionListener() {
         mHomeTransitionListener = new IHomeTransitionListener.Stub() {
             @Override
             public void onHomeVisibilityChanged(boolean isVisible) {
                 MAIN_EXECUTOR.execute(() -> {
-                    if (mLauncher.getTaskbarUIController() != null) {
+                    if (mLauncher != null && mLauncher.getTaskbarUIController() != null) {
                         mLauncher.getTaskbarUIController().onLauncherVisibilityChanged(isVisible);
                     }
                 });
@@ -53,5 +50,6 @@
     public void unregisterHomeTransitionListener() {
         SystemUiProxy.INSTANCE.get(mLauncher).setHomeTransitionListener(null);
         mHomeTransitionListener = null;
+        mLauncher = null;
     }
 }
diff --git a/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java b/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java
index a065387..f45ddb6 100644
--- a/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java
+++ b/quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java
@@ -266,8 +266,8 @@
         mAppTransitionManager.registerRemoteTransitions();
 
         if (FeatureFlags.enableHomeTransitionListener()) {
-            mHomeTransitionController = new HomeTransitionController(this);
-            mHomeTransitionController.registerHomeTransitionListener();
+            mHomeTransitionController = new HomeTransitionController();
+            mHomeTransitionController.registerHomeTransitionListener(this);
         }
 
         mTISBindHelper = new TISBindHelper(this, this::onTISConnected);