DO NOT MERGE Prevent back navigation not working after activity re-created am: 338e956022

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21166958

Change-Id: I1329869eea34cf8f88c38adb397da9c63e7dbb2a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

core/java/android/view/ViewRootImpl.java

@@ -8632,6 +8632,8 @@ public final class ViewRootImpl implements ViewParent,
 
         mInsetsController.dump(prefix, writer);
 
+        mOnBackInvokedDispatcher.dump(prefix, writer);
+
         writer.println(prefix + "View Hierarchy:");
         dumpViewHierarchy(innerPrefix, writer, mView);
     }

core/java/android/window/ImeOnBackInvokedDispatcher.java

@@ -211,6 +211,12 @@ public class ImeOnBackInvokedDispatcher implements OnBackInvokedDispatcher, Parc
         IOnBackInvokedCallback getIOnBackInvokedCallback() {
             return mIOnBackInvokedCallback;
         }
+
+        @Override
+        public String toString() {
+            return "ImeCallback=ImeOnBackInvokedCallback@" + mId
+                    + " Callback=" + mIOnBackInvokedCallback;
+        }
     }
 
     /**

core/java/android/window/ProxyOnBackInvokedDispatcher.java

@@ -179,16 +179,7 @@ public class ProxyOnBackInvokedDispatcher implements OnBackInvokedDispatcher {
                 return;
             }
             clearCallbacksOnDispatcher();
-            if (actualDispatcher instanceof ProxyOnBackInvokedDispatcher) {
+            mActualDispatcher = actualDispatcher;
-                // We don't want to nest ProxyDispatchers, so if we are given on, we unwrap its
-                // actual dispatcher.
-                // This can happen when an Activity is recreated but the Window is preserved (e.g.
-                // when going from split-screen back to single screen)
-                mActualDispatcher =
-                        ((ProxyOnBackInvokedDispatcher) actualDispatcher).mActualDispatcher;
-            } else {
-                mActualDispatcher = actualDispatcher;
-            }
             transferCallbacksToDispatcher();
         }
     }

core/java/android/window/WindowOnBackInvokedDispatcher.java

@@ -27,6 +27,7 @@ import android.util.Log;
 import android.view.IWindow;
 import android.view.IWindowSession;
 
+import java.io.PrintWriter;
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -221,6 +222,26 @@ public class WindowOnBackInvokedDispatcher implements OnBackInvokedDispatcher {
     @NonNull
     private static final BackProgressAnimator mProgressAnimator = new BackProgressAnimator();
 
+    /**
+     * Dump information about this WindowOnBackInvokedDispatcher
+     * @param prefix the prefix that will be prepended to each line of the produced output
+     * @param writer the writer that will receive the resulting text
+     */
+    public void dump(String prefix, PrintWriter writer) {
+        String innerPrefix = prefix + "    ";
+        writer.println(prefix + "WindowOnBackDispatcher:");
+        if (mAllCallbacks.isEmpty()) {
+            writer.println(prefix + "<None>");
+            return;
+        }
+
+        writer.println(innerPrefix + "Top Callback: " + getTopCallback());
+        writer.println(innerPrefix + "Callbacks: ");
+        mAllCallbacks.forEach((callback, priority) -> {
+            writer.println(innerPrefix + "  Callback: " + callback + " Priority=" + priority);
+        });
+    }
+
     static class OnBackInvokedCallbackWrapper extends IOnBackInvokedCallback.Stub {
         private final WeakReference<OnBackInvokedCallback> mCallback;
 

core/java/com/android/internal/policy/PhoneWindow.java

@@ -379,8 +379,12 @@ public class PhoneWindow extends Window implements MenuBuilder.Callback {
             // window, as we'll be skipping the addView in handleResumeActivity(), and
             // the token will not be updated as for a new window.
             getAttributes().token = preservedWindow.getAttributes().token;
-            mProxyOnBackInvokedDispatcher.setActualDispatcher(
+            final ViewRootImpl viewRoot = mDecor.getViewRootImpl();
-                    preservedWindow.getOnBackInvokedDispatcher());
+            if (viewRoot != null) {
+                // Clear the old callbacks and attach to the new window.
+                viewRoot.getOnBackInvokedDispatcher().clear();
+                onViewRootImplSet(viewRoot);
+            }
         }
         // Even though the device doesn't support picture-in-picture mode,
         // an user can force using it through developer options.