DO NOT MERGE Rename BackEvent to BackMotionEvent in LauncherBackAnimationController.

This cherry-picks ag/20484685 to QPR to mitigate future merge conflicts.

Bug: 238475284
Test: m -j
Change-Id: Ie13c738d0d4a10f4265fbf116ff7b4206d3bfc62
diff --git a/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java b/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java
index 2741751..3edbbdf 100644
--- a/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java
+++ b/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java
@@ -36,6 +36,7 @@
 import android.view.animation.AnimationUtils;
 import android.view.animation.Interpolator;
 import android.window.BackEvent;
+import android.window.BackMotionEvent;
 import android.window.BackProgressAnimator;
 import android.window.IOnBackInvokedCallback;
 
@@ -134,14 +135,14 @@
             }
 
             @Override
-            public void onBackProgressed(BackEvent backEvent) {
+            public void onBackProgressed(BackMotionEvent backEvent) {
                 handler.post(() -> {
                     mProgressAnimator.onBackProgressed(backEvent);
                 });
             }
 
             @Override
-            public void onBackStarted(BackEvent backEvent) {
+            public void onBackStarted(BackMotionEvent backEvent) {
                 handler.post(() -> {
                     startBack(backEvent);
                     mProgressAnimator.onBackStarted(backEvent, event -> {
@@ -185,7 +186,7 @@
         mBackCallback = null;
     }
 
-    private void startBack(BackEvent backEvent) {
+    private void startBack(BackMotionEvent backEvent) {
         mBackInProgress = true;
         RemoteAnimationTarget appTarget = backEvent.getDepartingAnimationTarget();