[STL] Fix predictive back with activity-compose:1.10.0-alpha03

activity-compose:1.10.0-alpha03 introduced a stricter coroutine
cancellation policy. The coroutine is now cancelled immediately when the
PredictiveBackHandler is disabled. Therefore we have to run the
transition on the animation scope instead.

Bug: 376154092
Flag: EXEMPT bugfix
Test: PredictiveBackHandlerTest
Change-Id: I2c9eda8c6c51335c547b10430ecfb34db02752f0

2 files changed, 18 insertions, 6 deletions

diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/PredictiveBackHandler.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/PredictiveBackHandler.kt
index b00c8ade07eb..8a6a0d6dbb99 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/PredictiveBackHandler.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/PredictiveBackHandler.kt
@@ -70,6 +70,7 @@ internal fun PredictiveBackHandler(
             // The predictive back APIs will automatically animate the progress for us in this case
             // so there is no need to animate it.
             cancelSpec = snap(),
+            animationScope = layoutImpl.animationScope,
         )
     }
 }
diff --git a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/transition/Seek.kt b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/transition/Seek.kt
index 715d979e116e..2b33224022fc 100644
--- a/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/transition/Seek.kt
+++ b/packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/transition/Seek.kt
@@ -30,6 +30,8 @@ import com.android.compose.animation.scene.TransitionKey
 import com.android.compose.animation.scene.UserActionResult
 import com.android.compose.animation.scene.createSwipeAnimation
 import kotlin.coroutines.cancellation.CancellationException
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.collectLatest
@@ -141,6 +143,7 @@ internal suspend fun <T : ContentKey> animateProgress(
     progress: Flow<Float>,
     commitSpec: AnimationSpec<Float>?,
     cancelSpec: AnimationSpec<Float>?,
+    animationScope: CoroutineScope? = null,
 ) {
     fun animateOffset(targetContent: T, spec: AnimationSpec<Float>?) {
         if (state.transitionState != animation.contentTransition || animation.isAnimatingOffset()) {
@@ -176,12 +179,20 @@ internal suspend fun <T : ContentKey> animateProgress(
         }
 
         // Start the transition.
-        state.startTransition(animation.contentTransition)
+        animationScope?.launch { startTransition(state, animation, collectionJob) }
+            ?: startTransition(state, animation, collectionJob)
+    }
+}
 
-        // The transition is done. Cancel the collection in case the transition was finished because
-        // it was interrupted by another transition.
-        if (collectionJob.isActive) {
-            collectionJob.cancel()
-        }
+private suspend fun <T : ContentKey> startTransition(
+    state: MutableSceneTransitionLayoutStateImpl,
+    animation: SwipeAnimation<T>,
+    progressCollectionJob: Job,
+) {
+    state.startTransition(animation.contentTransition)
+    // The transition is done. Cancel the collection in case the transition was finished
+    // because it was interrupted by another transition.
+    if (progressCollectionJob.isActive) {
+        progressCollectionJob.cancel()
     }
 }