migrate deprecated onBackPressed() (#51096)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/51096

**Problem:** `Activity.onBackPressed()` has been deprecated and with targetSdk 36, predictive back will be enforced and the API no longer called. We need to migrate to backward compatible AndroidX `OnBackPressedCallback`.
- https://developer.android.com/about/versions/16/behavior-changes-16#predictive-back.

**Solution:**
`OnBackPressedCallback` is registered conditionally only if it is `targetSdk` 36 or greater.
If the callback in enabled, `onBackPressed()` is not called and callback is used regardless of `android:enableOnBackInvokedCallback` property in <application> or <activity> set in AndroidManifest.xml.

As a workaround callback is manually calling existing `onBackPressed()`.

This is done rather than removing onBackPressed() completely and using only `OnBackPressedCallback` as we are not sure of the impact of removing the implementation entirely. Once we determine it is safe to do so then, we should remove the workaround and fully transition to `OnBackPressedCallback`

* I also surveyed child classes extending ReactActivity for overridden `onPressedBack()` usage and found only one usage which will be handled later.

NOTE: `ReactDelegate.onHostResume()` sets up the `DefaultHardwareBackBtnHandler` using `ReactActivity` (https://fburl.com/ul47tbeo) and will be called from JS `BackHanderl.exitApp` (https://fburl.com/code/a4l2pjsw). Calling `BackHanderl.exitApp` enables predictive back to work.

Changelog:
[Internal]

Reviewed By: mdvacca

Differential Revision: D74161428

fbshipit-source-id: 2e081ba6922b315e9d1746e83a41bab5277fa62e

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactActivity.java

@@ -11,11 +11,13 @@ import android.content.Intent;
 import android.content.res.Configuration;
 import android.os.Bundle;
 import android.view.KeyEvent;
+import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
 import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
 import com.facebook.react.modules.core.PermissionAwareActivity;
 import com.facebook.react.modules.core.PermissionListener;
+import com.facebook.react.util.AndroidVersion;
 import org.jetbrains.annotations.NotNull;
 
 /** Base Activity for React Native applications. */
@@ -24,6 +26,18 @@ public abstract class ReactActivity extends AppCompatActivity
 
   private final ReactActivityDelegate mDelegate;
 
+  // Due to enforced predictive back on targetSdk 36, 'onBackPressed()' is disabled by default.
+  // Using a workaround to trigger it manually.
+  private final OnBackPressedCallback mBackPressedCallback =
+      new OnBackPressedCallback(true) {
+        @Override
+        public void handleOnBackPressed() {
+          setEnabled(false);
+          onBackPressed();
+          setEnabled(true);
+        }
+      };
+
   protected ReactActivity() {
     mDelegate = createReactActivityDelegate();
   }
@@ -45,6 +59,9 @@ public abstract class ReactActivity extends AppCompatActivity
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     mDelegate.onCreate(savedInstanceState);
+    if (AndroidVersion.isAtLeastTargetSdk36(this)) {
+      getOnBackPressedDispatcher().addCallback(this, mBackPressedCallback);
+    }
   }
 
   @Override
@@ -103,6 +120,9 @@ public abstract class ReactActivity extends AppCompatActivity
 
   @Override
   public void invokeDefaultOnBackPressed() {
+    // Disabling callback so the fallback logic (finish activity) can run
+    // as super.onBackPressed() will call all enabled callbacks in the dispatcher.
+    mBackPressedCallback.setEnabled(false);
     super.onBackPressed();
   }
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/util/AndroidVersion.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.util
+
+import android.content.Context
+import android.os.Build
+
+/** Helper class for checking Android version-related information. */
+internal object AndroidVersion {
+
+  /**
+   * This is the version code for Android 16 (SDK Level 36). Delete it once we bump up the default
+   * compile SDK version to 36.
+   */
+  private const val VERSION_CODE_BAKLAVA: Int = 36
+
+  /**
+   * This method is used to check if the current device is running Android 16 (SDK Level 36) or
+   * higher and the app is targeting Android 16 (SDK Level 36) or higher.
+   */
+  @JvmStatic
+  fun isAtLeastTargetSdk36(context: Context): Boolean =
+      Build.VERSION.SDK_INT >= VERSION_CODE_BAKLAVA &&
+          context.applicationInfo.targetSdkVersion >= VERSION_CODE_BAKLAVA
+}