Fix regression in semantics update handling. (#165842)

This was shown with the following errors in stdout:
GLib-GObject-CRITICAL **: 11:41:35.775: invalid cast from 'FlEngine' to
'FlView'

This was broken in 554c814ada

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -53327,6 +53327,7 @@ ORIGIN: ../../../flutter/shell/platform/linux/fl_view.cc + ../../../flutter/LICE
 ORIGIN: ../../../flutter/shell/platform/linux/fl_view_accessible.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/linux/fl_view_accessible.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/linux/fl_view_accessible_test.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/linux/fl_view_private.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/linux/fl_view_test.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/linux/fl_window_state_monitor.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/linux/fl_window_state_monitor.h + ../../../flutter/LICENSE
@@ -56336,6 +56337,7 @@ FILE: ../../../flutter/shell/platform/linux/fl_view.cc
 FILE: ../../../flutter/shell/platform/linux/fl_view_accessible.cc
 FILE: ../../../flutter/shell/platform/linux/fl_view_accessible.h
 FILE: ../../../flutter/shell/platform/linux/fl_view_accessible_test.cc
+FILE: ../../../flutter/shell/platform/linux/fl_view_private.h
 FILE: ../../../flutter/shell/platform/linux/fl_view_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_window_state_monitor.cc
 FILE: ../../../flutter/shell/platform/linux/fl_window_state_monitor.h

engine/src/flutter/shell/platform/linux/BUILD.gn

@@ -91,6 +91,7 @@ source_set("flutter_linux_sources") {
              "fl_method_codec_private.h",
              "fl_plugin_registrar_private.h",
              "fl_pointer_manager.h",
+             "fl_view_private.h",
              "fl_window_state_monitor.h",
              "key_mapping.h",
            ]

engine/src/flutter/shell/platform/linux/fl_view.cc

@@ -20,6 +20,7 @@
 #include "flutter/shell/platform/linux/fl_socket_accessible.h"
 #include "flutter/shell/platform/linux/fl_touch_manager.h"
 #include "flutter/shell/platform/linux/fl_view_accessible.h"
+#include "flutter/shell/platform/linux/fl_view_private.h"
 #include "flutter/shell/platform/linux/fl_window_state_monitor.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_engine.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_plugin_registry.h"
@@ -222,11 +223,8 @@ static void view_added_cb(GObject* object,
 }
 
 // Called when the engine updates accessibility.
-static void update_semantics_cb(FlEngine* engine,
-                                const FlutterSemanticsUpdate2* update,
-                                gpointer user_data) {
-  FlView* self = FL_VIEW(user_data);
-
+static void update_semantics_cb(FlView* self,
+                                const FlutterSemanticsUpdate2* update) {
   // A semantics update is routed to a particular view.
   if (update->view_id != self->view_id) {
     return;
@@ -496,11 +494,6 @@ static void realize_cb(FlView* self) {
   setup_cursor(self);
 
   handle_geometry_changed(self);
-
-  self->view_accessible = fl_view_accessible_new(self->engine, self->view_id);
-  fl_socket_accessible_embed(
-      FL_SOCKET_ACCESSIBLE(gtk_widget_get_accessible(GTK_WIDGET(self))),
-      atk_plug_get_id(ATK_PLUG(self->view_accessible)));
 }
 
 static void secondary_realize_cb(FlView* self) {
@@ -685,6 +678,22 @@ static void fl_view_class_init(FlViewClass* klass) {
                                        fl_socket_accessible_get_type());
 }
 
+// Engine related construction.
+static void setup_engine(FlView* self) {
+  self->view_accessible = fl_view_accessible_new(self->engine, self->view_id);
+  fl_socket_accessible_embed(
+      FL_SOCKET_ACCESSIBLE(gtk_widget_get_accessible(GTK_WIDGET(self))),
+      atk_plug_get_id(ATK_PLUG(self->view_accessible)));
+
+  self->pointer_manager = fl_pointer_manager_new(self->view_id, self->engine);
+
+  self->on_pre_engine_restart_cb_id =
+      g_signal_connect_swapped(self->engine, "on-pre-engine-restart",
+                               G_CALLBACK(on_pre_engine_restart_cb), self);
+  self->update_semantics_cb_id = g_signal_connect_swapped(
+      self->engine, "update-semantics", G_CALLBACK(update_semantics_cb), self);
+}
+
 static void fl_view_init(FlView* self) {
   self->cancellable = g_cancellable_new();
 
@@ -755,13 +764,7 @@ G_MODULE_EXPORT FlView* fl_view_new(FlDartProject* project) {
   g_assert(FL_IS_RENDERER_GDK(renderer));
   self->renderer = FL_RENDERER_GDK(g_object_ref(renderer));
 
-  self->pointer_manager = fl_pointer_manager_new(self->view_id, engine);
-
-  self->on_pre_engine_restart_cb_id =
-      g_signal_connect_swapped(self->engine, "on-pre-engine-restart",
-                               G_CALLBACK(on_pre_engine_restart_cb), self);
-  self->update_semantics_cb_id = g_signal_connect_swapped(
-      engine, "update-semantics", G_CALLBACK(update_semantics_cb), self);
+  setup_engine(self);
 
   g_signal_connect_swapped(self->gl_area, "create-context",
                            G_CALLBACK(create_context_cb), self);
@@ -781,18 +784,14 @@ G_MODULE_EXPORT FlView* fl_view_new_for_engine(FlEngine* engine) {
   g_assert(FL_IS_RENDERER_GDK(renderer));
   self->renderer = FL_RENDERER_GDK(g_object_ref(renderer));
 
-  self->on_pre_engine_restart_cb_id =
-      g_signal_connect_swapped(engine, "on-pre-engine-restart",
-                               G_CALLBACK(on_pre_engine_restart_cb), self);
-
   self->view_id = fl_engine_add_view(engine, 1, 1, 1.0, self->cancellable,
                                      view_added_cb, self);
 
+  setup_engine(self);
+
   fl_renderer_add_renderable(FL_RENDERER(self->renderer), self->view_id,
                              FL_RENDERABLE(self));
 
-  self->pointer_manager = fl_pointer_manager_new(self->view_id, engine);
-
   g_signal_connect_swapped(self->gl_area, "realize",
                            G_CALLBACK(secondary_realize_cb), self);
   return self;
@@ -815,3 +814,8 @@ G_MODULE_EXPORT void fl_view_set_background_color(FlView* self,
   gdk_rgba_free(self->background_color);
   self->background_color = gdk_rgba_copy(color);
 }
+
+FlViewAccessible* fl_view_get_accessible(FlView* self) {
+  g_return_val_if_fail(FL_IS_VIEW(self), nullptr);
+  return self->view_accessible;
+}

engine/src/flutter/shell/platform/linux/fl_view_accessible.cc

@@ -143,6 +143,8 @@ FlViewAccessible* fl_view_accessible_new(FlEngine* engine,
 void fl_view_accessible_handle_update_semantics(
     FlViewAccessible* self,
     const FlutterSemanticsUpdate2* update) {
+  g_return_if_fail(FL_IS_VIEW_ACCESSIBLE(self));
+
   g_autoptr(GHashTable) pending_children =
       g_hash_table_new_full(g_direct_hash, g_direct_equal, nullptr,
                             reinterpret_cast<GDestroyNotify>(fl_value_unref));

engine/src/flutter/shell/platform/linux/fl_view_private.h

@@ -0,0 +1,25 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_LINUX_FL_VIEW_PRIVATE_H_
+#define FLUTTER_SHELL_PLATFORM_LINUX_FL_VIEW_PRIVATE_H_
+
+#include "flutter/shell/platform/linux/fl_view_accessible.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_view.h"
+
+G_BEGIN_DECLS
+
+/**
+ * fl_view_get_accessible:
+ * @view: an #FlView.
+ *
+ * Get the accessible object for this view.
+ *
+ * Returns: an #FlViewAccessible.
+ */
+FlViewAccessible* fl_view_get_accessible(FlView* view);
+
+G_END_DECLS
+
+#endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_VIEW_PRIVATE_H_

engine/src/flutter/shell/platform/linux/fl_view_test.cc

@@ -5,6 +5,7 @@
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_view.h"
 #include "flutter/shell/platform/embedder/test_utils/proc_table_replacement.h"
 #include "flutter/shell/platform/linux/fl_engine_private.h"
+#include "flutter/shell/platform/linux/fl_view_private.h"
 #include "flutter/shell/platform/linux/testing/fl_test.h"
 #include "flutter/shell/platform/linux/testing/fl_test_gtk_logs.h"
 #include "flutter/shell/platform/linux/testing/mock_gtk.h"
@@ -61,6 +62,57 @@ TEST(FlViewTest, FirstFrameSignal) {
   EXPECT_TRUE(first_frame_emitted);
 }
 
+// Check semantics update applied
+TEST(FlViewTest, SemanticsUpdate) {
+  flutter::testing::fl_ensure_gtk_init();
+
+  g_autoptr(FlDartProject) project = fl_dart_project_new();
+  FlView* view = fl_view_new(project);
+
+  FlEngine* engine = fl_view_get_engine(view);
+  g_autoptr(GError) error = nullptr;
+  EXPECT_TRUE(fl_engine_start(engine, &error));
+
+  FlutterSemanticsNode2 root_node = {
+      .id = 0,
+      .label = "root",
+  };
+  FlutterSemanticsNode2* nodes[1] = {&root_node};
+  FlutterSemanticsUpdate2 update = {
+      .node_count = 1, .nodes = nodes, .view_id = 0};
+  g_signal_emit_by_name(engine, "update-semantics", &update);
+
+  FlViewAccessible* accessible = fl_view_get_accessible(view);
+  EXPECT_EQ(atk_object_get_n_accessible_children(ATK_OBJECT(accessible)), 1);
+  AtkObject* root_object =
+      atk_object_ref_accessible_child(ATK_OBJECT(accessible), 0);
+  EXPECT_STREQ(atk_object_get_name(root_object), "root");
+}
+
+// Check semantics update ignored for other view
+TEST(FlViewTest, SemanticsUpdateOtherView) {
+  flutter::testing::fl_ensure_gtk_init();
+
+  g_autoptr(FlDartProject) project = fl_dart_project_new();
+  FlView* view = fl_view_new(project);
+
+  FlEngine* engine = fl_view_get_engine(view);
+  g_autoptr(GError) error = nullptr;
+  EXPECT_TRUE(fl_engine_start(engine, &error));
+
+  FlutterSemanticsNode2 root_node = {
+      .id = 0,
+      .label = "root",
+  };
+  FlutterSemanticsNode2* nodes[1] = {&root_node};
+  FlutterSemanticsUpdate2 update = {
+      .node_count = 1, .nodes = nodes, .view_id = 99};
+  g_signal_emit_by_name(engine, "update-semantics", &update);
+
+  FlViewAccessible* accessible = fl_view_get_accessible(view);
+  EXPECT_EQ(atk_object_get_n_accessible_children(ATK_OBJECT(accessible)), 0);
+}
+
 // Check secondary view is registered with engine.
 TEST(FlViewTest, SecondaryView) {
   flutter::testing::fl_ensure_gtk_init();