From 04cb994830dd5ce917b611f49aa374e3526189a9 Mon Sep 17 00:00:00 2001
From: omarmt <omarmt@google.com>
Date: Tue, 25 Apr 2023 13:41:31 +0000
Subject: [PATCH] Verify enableOnBackInvokedCallback at the app-level if
 ActivityInfo is null

The `ActivityInfo` should not be `null`, otherwise we will not be able to check if the activity has the `enableOnBackInvokedCallback="true|false"` flag.

Unfortunately, there is no good default value in this case.

Our options are:
- Use the application flag, but this may cause random behavior that is difficult to troubleshoot.
- Assume that the activity has `enableOnBackInvokedCallback="false"` in the manifest, which might have strange behavior but at least it would be a "known issue" (for example, if you activate predictive back and it doesn't work in that activity, you can check that XYZ is correct).

Regardless of the reason, I would add a warning or error message explaining the problem.

Test: mp droid
Bug: 271860402
Change-Id: Ie91376ce18eb0a8d5528339a68e4db88a57cff86
---
 .../window/WindowOnBackInvokedDispatcher.java | 43 ++++++++++++-------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/core/java/android/window/WindowOnBackInvokedDispatcher.java b/core/java/android/window/WindowOnBackInvokedDispatcher.java
index 51382a4b265f4..4d0132e46ba7b 100644
--- a/core/java/android/window/WindowOnBackInvokedDispatcher.java
+++ b/core/java/android/window/WindowOnBackInvokedDispatcher.java
@@ -21,6 +21,8 @@ import android.annotation.Nullable;
 import android.app.Activity;
 import android.content.Context;
 import android.content.ContextWrapper;
+import android.content.pm.ActivityInfo;
+import android.content.pm.ApplicationInfo;
 import android.os.Handler;
 import android.os.RemoteException;
 import android.os.SystemProperties;
@@ -421,36 +423,45 @@ public class WindowOnBackInvokedDispatcher implements OnBackInvokedDispatcher {
                 return false;
             }
 
-            boolean requestsPredictiveBack;
+            boolean requestsPredictiveBack = false;
 
             // Check if the context is from an activity.
             while ((context instanceof ContextWrapper) && !(context instanceof Activity)) {
                 context = ((ContextWrapper) context).getBaseContext();
             }
 
+            boolean shouldCheckActivity = false;
+
             if (context instanceof Activity) {
                 final Activity activity = (Activity) context;
 
-                if (activity.getActivityInfo().hasOnBackInvokedCallbackEnabled()) {
-                    requestsPredictiveBack =
-                            activity.getActivityInfo().isOnBackInvokedCallbackEnabled();
-                } else {
-                    requestsPredictiveBack =
-                            context.getApplicationInfo().isOnBackInvokedCallbackEnabled();
-                }
+                final ActivityInfo activityInfo = activity.getActivityInfo();
+                if (activityInfo != null) {
+                    if (activityInfo.hasOnBackInvokedCallbackEnabled()) {
+                        shouldCheckActivity = true;
+                        requestsPredictiveBack = activityInfo.isOnBackInvokedCallbackEnabled();
 
-                if (DEBUG) {
-                    Log.d(TAG, TextUtils.formatSimple("Activity: %s isPredictiveBackEnabled=%s",
-                            activity.getComponentName(),
-                            requestsPredictiveBack));
+                        if (DEBUG) {
+                            Log.d(TAG, TextUtils.formatSimple(
+                                    "Activity: %s isPredictiveBackEnabled=%s",
+                                    activity.getComponentName(),
+                                    requestsPredictiveBack));
+                        }
+                    }
+                } else {
+                    Log.w(TAG, "The ActivityInfo is null, so we cannot verify if this Activity"
+                            + " has the 'android:enableOnBackInvokedCallback' attribute."
+                            + " The application attribute will be used as a fallback.");
                 }
-            } else {
-                requestsPredictiveBack =
-                        context.getApplicationInfo().isOnBackInvokedCallbackEnabled();
+            }
+
+            if (!shouldCheckActivity) {
+                final ApplicationInfo applicationInfo = context.getApplicationInfo();
+                requestsPredictiveBack = applicationInfo.isOnBackInvokedCallbackEnabled();
 
                 if (DEBUG) {
                     Log.d(TAG, TextUtils.formatSimple("App: %s requestsPredictiveBack=%s",
-                            context.getApplicationInfo().packageName,
+                            applicationInfo.packageName,
                             requestsPredictiveBack));
                 }
             }