Use STANDARD_DECELERATE interpolator for predictive back to home

Bug: 325647546
Flag: ACONFIG com.android.systemui.predictive_back_system_animations TEAMFOOD
Test: Manual, i.e. verifying increased responsiveness during first phase of back gesture
Change-Id: Ie31d7fba7ca307c96830e0656887cda89d9bbb1a
diff --git a/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java b/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java
index 5772450..364d9dc 100644
--- a/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java
+++ b/quickstep/src/com/android/quickstep/LauncherBackAnimationController.java
@@ -52,6 +52,7 @@
 import android.window.BackProgressAnimator;
 import android.window.IOnBackInvokedCallback;
 
+import com.android.app.animation.Interpolators;
 import com.android.internal.view.AppearanceRegion;
 import com.android.launcher3.AbstractFloatingView;
 import com.android.launcher3.BubbleTextView;
@@ -103,7 +104,8 @@
     private float mWindowScaleEndCornerRadius;
     private float mWindowScaleStartCornerRadius;
     private final Interpolator mCancelInterpolator;
-    private final Interpolator mProgressInterpolator = new DecelerateInterpolator();
+    private final Interpolator mProgressInterpolator = Interpolators.STANDARD_DECELERATE;
+    private final Interpolator mVerticalMoveInterpolator = new DecelerateInterpolator();
     private final PointF mInitialTouchPos = new PointF();
 
     private RemoteAnimationTarget mBackTarget;
@@ -376,7 +378,7 @@
         float yDirection = rawYDelta < 0 ? -1 : 1;
         // limit yDelta interpretation to 1/2 of screen height in either direction
         float deltaYRatio = Math.min(screenHeight / 2f, Math.abs(rawYDelta)) / (screenHeight / 2f);
-        float interpolatedYRatio = mProgressInterpolator.getInterpolation(deltaYRatio);
+        float interpolatedYRatio = mVerticalMoveInterpolator.getInterpolation(deltaYRatio);
         // limit y-shift so surface never passes 8dp screen margin
         float deltaY = yDirection * interpolatedYRatio * Math.max(0f, (screenHeight - height)
                 / 2f - mWindowScaleMarginX);