Merge "Transfer the actual dispatcher when the window is preserved" into tm-dev

core/java/android/window/ProxyOnBackInvokedDispatcher.java

@@ -90,10 +90,14 @@ public class ProxyOnBackInvokedDispatcher implements OnBackInvokedDispatcher {
         synchronized (mLock) {
             mCallbacks.add(Pair.create(callback, priority));
             if (mActualDispatcher != null) {
+                if (priority <= PRIORITY_SYSTEM) {
+                    mActualDispatcher.registerSystemOnBackInvokedCallback(callback);
+                } else {
                     mActualDispatcher.registerOnBackInvokedCallback(priority, callback);
                 }
             }
         }
+    }
 
     /**
      * Transfers all the pending callbacks to the provided dispatcher.
@@ -171,7 +175,16 @@ public class ProxyOnBackInvokedDispatcher implements OnBackInvokedDispatcher {
                 return;
             }
             clearCallbacksOnDispatcher();
+            if (actualDispatcher instanceof ProxyOnBackInvokedDispatcher) {
+                // 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/com/android/internal/policy/PhoneWindow.java

@@ -342,7 +342,7 @@ public class PhoneWindow extends Window implements MenuBuilder.Callback {
 
     boolean mDecorFitsSystemWindows = true;
 
-    private ProxyOnBackInvokedDispatcher mProxyOnBackInvokedDispatcher =
+    private final ProxyOnBackInvokedDispatcher mProxyOnBackInvokedDispatcher =
             new ProxyOnBackInvokedDispatcher();
 
     static class WindowManagerHolder {
@@ -378,6 +378,8 @@ 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(
+                    preservedWindow.getOnBackInvokedDispatcher());
         }
         // Even though the device doesn't support picture-in-picture mode,
         // an user can force using it through developer options.