From f5e3ece92864d1cf72566afa672d8d873bfe000f Mon Sep 17 00:00:00 2001
From: Evan Rosky <erosky@google.com>
Date: Wed, 7 Aug 2024 11:22:35 -0700
Subject: Small preventative fixes/refactors

Some minor re-arrangement to improve correctness
and reduce dependencies. For example, this was only
checking some activities to see if transition is "no-op"
when it should be checking the transition itself
in-case there were some unexpected changes.

Bug: 340386663
Test: existing tests
Flag: com.android.window.flags.migrate_predictive_back_transition
Change-Id: Ie0326940090645b0c04e673d849c039cd5b86658
---
 .../com/android/server/wm/BackNavigationController.java     | 13 +++----------
 services/core/java/com/android/server/wm/Transition.java    |  9 +++++++++
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/services/core/java/com/android/server/wm/BackNavigationController.java b/services/core/java/com/android/server/wm/BackNavigationController.java
index b4c75572d68f..06e665e88b65 100644
--- a/services/core/java/com/android/server/wm/BackNavigationController.java
+++ b/services/core/java/com/android/server/wm/BackNavigationController.java
@@ -1935,8 +1935,7 @@ class BackNavigationController {
             for (int i = penActivities.length - 1; i >= 0; --i) {
                 ActivityRecord resetActivity = penActivities[i];
                 if (transition.isInTransition(resetActivity)) {
-                    resetActivity.mTransitionController.setReady(
-                            resetActivity.getDisplayContent(), true);
+                    transition.setReady(resetActivity.getDisplayContent(), true);
                     return true;
                 }
             }
@@ -1991,18 +1990,12 @@ class BackNavigationController {
                 activity.makeVisibleIfNeeded(null /* starting */, true /* notifyToClient */);
             }
         }
-        boolean needTransition = false;
-        final DisplayContent dc = affects.get(0).getDisplayContent();
-        for (int i = affects.size() - 1; i >= 0; --i) {
-            final ActivityRecord activity = affects.get(i);
-            needTransition |= tc.isCollecting(activity);
-        }
         if (prepareOpen != null) {
-            if (needTransition) {
+            if (prepareOpen.hasChanges()) {
                 tc.requestStartTransition(prepareOpen,
                         null /*startTask */, null /* remoteTransition */,
                         null /* displayChange */);
-                tc.setReady(dc);
+                prepareOpen.setReady(affects.get(0), true);
                 return prepareOpen;
             } else {
                 prepareOpen.abort();
diff --git a/services/core/java/com/android/server/wm/Transition.java b/services/core/java/com/android/server/wm/Transition.java
index 5698750170f4..57a9aba2f4a3 100644
--- a/services/core/java/com/android/server/wm/Transition.java
+++ b/services/core/java/com/android/server/wm/Transition.java
@@ -3350,6 +3350,15 @@ class Transition implements BLASTSyncEngine.TransactionReadyListener {
         return chg.hasChanged();
     }
 
+    boolean hasChanges() {
+        for (int i = 0; i < mParticipants.size(); ++i) {
+            if (mChanges.get(mParticipants.valueAt(i)).hasChanged()) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     @VisibleForTesting
     static class ChangeInfo {
         private static final int FLAG_NONE = 0;
-- 
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