Bring cross-activity back animation spec closer to forward animation

Bug: 343136429
Flag: com.android.window.flags.predictive_back_system_anims NEXTFOOD
Test: Manual, i.e. testing forward and backward animations on device
Change-Id: I677c17d19f82ba4be98139b4e29cd76b6788d211

libs/WindowManager/Shell/src/com/android/wm/shell/back/DefaultCrossActivityBackAnimation.kt

@@ -43,7 +43,7 @@ constructor(
         Choreographer.getInstance()
     ) {
 
-    private val postCommitInterpolator = Interpolators.FAST_OUT_SLOW_IN
+    private val postCommitInterpolator = Interpolators.EMPHASIZED
     private val enteringStartOffset =
         context.resources.getDimension(R.dimen.cross_activity_back_entering_start_offset)
     override val allowEnteringYShift = true
@@ -87,7 +87,7 @@ constructor(
 
     override fun onPostCommitProgress(linearProgress: Float) {
         super.onPostCommitProgress(linearProgress)
-        val closingAlpha = max(1f - linearProgress * 2, 0f)
+        val closingAlpha = max(1f - linearProgress * 5, 0f)
         val progress = postCommitInterpolator.getInterpolation(linearProgress)
         currentClosingRect.setInterpolatedRectF(startClosingRect, targetClosingRect, progress)
         applyTransform(closingTarget?.leash, currentClosingRect, closingAlpha)
@@ -98,6 +98,6 @@ constructor(
 
 
     companion object {
-        private const val POST_COMMIT_DURATION = 300L
+        private const val POST_COMMIT_DURATION = 450L
     }
 }