Fix AlertDialogs built by platform views (#17511)

shell/platform/android/io/flutter/plugin/platform/SingleViewPresentation.java

@@ -9,6 +9,7 @@ import static android.content.Context.WINDOW_SERVICE;
 import static android.view.View.OnFocusChangeListener;
 
 import android.annotation.TargetApi;
+import android.app.AlertDialog;
 import android.app.Presentation;
 import android.content.Context;
 import android.content.ContextWrapper;
@@ -102,6 +103,9 @@ class SingleViewPresentation extends Presentation {
 
   private boolean startFocused = false;
 
+  // The context for the application window that hosts FlutterView.
+  private final Context outerContext;
+
   /**
    * Creates a presentation that will use the view factory to create a new platform view in the
    * presentation's onCreate, and attach it.
@@ -120,6 +124,7 @@ class SingleViewPresentation extends Presentation {
     this.viewId = viewId;
     this.createParams = createParams;
     this.focusChangeListener = focusChangeListener;
+    this.outerContext = outerContext;
     state = new PresentationState();
     getWindow()
         .setFlags(
@@ -147,6 +152,7 @@ class SingleViewPresentation extends Presentation {
     viewFactory = null;
     this.state = state;
     this.focusChangeListener = focusChangeListener;
+    this.outerContext = outerContext;
     getWindow()
         .setFlags(
             WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
@@ -173,7 +179,8 @@ class SingleViewPresentation extends Presentation {
 
     // Our base mContext has already been wrapped with an IMM cache at instantiation time, but
     // we want to wrap it again here to also return state.windowManagerHandler.
-    Context context = new PresentationContext(getContext(), state.windowManagerHandler);
+    Context context =
+        new PresentationContext(getContext(), state.windowManagerHandler, outerContext);
 
     if (state.platformView == null) {
       state.platformView = viewFactory.create(context, viewId, createParams);
@@ -304,15 +311,34 @@ class SingleViewPresentation extends Presentation {
   private static class PresentationContext extends ContextWrapper {
     private @NonNull final WindowManagerHandler windowManagerHandler;
     private @Nullable WindowManager windowManager;
+    private final Context flutterAppWindowContext;
 
-    PresentationContext(Context base, @NonNull WindowManagerHandler windowManagerHandler) {
+    PresentationContext(
+        Context base,
+        @NonNull WindowManagerHandler windowManagerHandler,
+        Context flutterAppWindowContext) {
       super(base);
       this.windowManagerHandler = windowManagerHandler;
+      this.flutterAppWindowContext = flutterAppWindowContext;
     }
 
     @Override
     public Object getSystemService(String name) {
       if (WINDOW_SERVICE.equals(name)) {
+        if (isCalledFromAlertDialog()) {
+          // Alert dialogs are showing on top of the entire application and should not be limited to
+          // the virtual
+          // display. If we detect that an android.app.AlertDialog constructor is what's fetching
+          // the window manager
+          // we return the one for the application's window.
+          //
+          // Note that if we don't do this AlertDialog will throw a ClassCastException as down the
+          // line it tries
+          // to case this instance to a WindowManagerImpl which the object returned by
+          // getWindowManager is not
+          // a subclass of.
+          return flutterAppWindowContext.getSystemService(name);
+        }
         return getWindowManager();
       }
       return super.getSystemService(name);
@@ -324,6 +350,17 @@ class SingleViewPresentation extends Presentation {
       }
       return windowManager;
     }
+
+    private boolean isCalledFromAlertDialog() {
+      StackTraceElement[] stackTraceElements = Thread.currentThread().getStackTrace();
+      for (int i = 0; i < stackTraceElements.length && i < 11; i++) {
+        if (stackTraceElements[i].getClassName().equals(AlertDialog.class.getCanonicalName())
+            && stackTraceElements[i].getMethodName().equals("<init>")) {
+          return true;
+        }
+      }
+      return false;
+    }
   }
 
   /*