Win32: Implement DispatchAccessibilityAction (flutter#30187)

Implements DispatchAccessibilityAction: a pass-through method that
forwards to the engine, which calls through the Embedder API back to the
framework.

Issue: flutter/flutter#77838

ci/licenses_golden/licenses_flutter

@@ -1697,6 +1697,7 @@ FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/fl_view.h
 FILE: ../../../flutter/shell/platform/linux/public/flutter_linux/flutter_linux.h
 FILE: ../../../flutter/shell/platform/windows/accessibility_bridge_delegate_win32.cc
 FILE: ../../../flutter/shell/platform/windows/accessibility_bridge_delegate_win32.h
+FILE: ../../../flutter/shell/platform/windows/accessibility_bridge_delegate_win32_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/accessibility_bridge_delegate_winuwp.cc
 FILE: ../../../flutter/shell/platform/windows/accessibility_bridge_delegate_winuwp.h
 FILE: ../../../flutter/shell/platform/windows/angle_surface_manager.cc

shell/platform/windows/BUILD.gn

@@ -251,6 +251,7 @@ executable("flutter_windows_unittests") {
   } else {
     sources += [
       # TODO move first two tests to common once above TODO's unblocked.
+      "accessibility_bridge_delegate_win32_unittests.cc",
       "dpi_utils_win32_unittests.cc",
       "flutter_project_bundle_unittests.cc",
       "flutter_window_win32_unittests.cc",

shell/platform/windows/accessibility_bridge_delegate_win32.cc

@@ -25,7 +25,7 @@ void AccessibilityBridgeDelegateWin32::DispatchAccessibilityAction(
     AccessibilityNodeId target,
     FlutterSemanticsAction action,
     fml::MallocMapping data) {
-  // TODO(cbracken): https://github.com/flutter/flutter/issues/77838
+  engine_->DispatchSemanticsAction(target, action, std::move(data));
 }
 
 std::shared_ptr<FlutterPlatformNodeDelegate>

shell/platform/windows/accessibility_bridge_delegate_win32_unittests.cc

@@ -0,0 +1,128 @@
+// 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.
+
+#include "flutter/shell/platform/windows/accessibility_bridge_delegate_win32.h"
+
+#include <comdef.h>
+#include <comutil.h>
+#include <oleacc.h>
+
+#include <vector>
+
+#include "flutter/shell/platform/embedder/embedder.h"
+#include "flutter/shell/platform/embedder/test_utils/proc_table_replacement.h"
+#include "flutter/shell/platform/windows/flutter_platform_node_delegate_win32.h"
+#include "flutter/shell/platform/windows/flutter_windows_engine.h"
+#include "flutter/shell/platform/windows/flutter_windows_view.h"
+#include "flutter/shell/platform/windows/testing/engine_modifier.h"
+#include "flutter/shell/platform/windows/testing/mock_window_binding_handler.h"
+#include "flutter/shell/platform/windows/testing/test_keyboard.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace flutter {
+namespace testing {
+
+namespace {
+
+// Returns an engine instance configured with dummy project path values, and
+// overridden methods for sending platform messages, so that the engine can
+// respond as if the framework were connected.
+std::unique_ptr<FlutterWindowsEngine> GetTestEngine() {
+  FlutterDesktopEngineProperties properties = {};
+  properties.assets_path = L"C:\\foo\\flutter_assets";
+  properties.icu_data_path = L"C:\\foo\\icudtl.dat";
+  properties.aot_library_path = L"C:\\foo\\aot.so";
+  FlutterProjectBundle project(properties);
+  auto engine = std::make_unique<FlutterWindowsEngine>(project);
+
+  EngineModifier modifier(engine.get());
+  modifier.embedder_api().UpdateSemanticsEnabled =
+      [](FLUTTER_API_SYMBOL(FlutterEngine) engine, bool enabled) {
+        return kSuccess;
+      };
+  MockEmbedderApiForKeyboard(
+      modifier, [] { return false; },
+      [](const FlutterKeyEvent* event) { return false; });
+
+  engine->RunWithEntrypoint(nullptr);
+  return engine;
+}
+
+// Populates the AXTree associated with the specified bridge with test data.
+//
+//        node0
+//        /   \
+//    node1    node2
+//             /   \
+//         node3   node4
+//
+// node0 and node2 are grouping nodes. node1 and node2 are static text nodes.
+// node4 is a static text node with no text, and hence has the "ignored" state.
+void PopulateAXTree(std::shared_ptr<AccessibilityBridge> bridge) {
+  // Add node 0: root.
+  FlutterSemanticsNode node0{sizeof(FlutterSemanticsNode), 0};
+  std::vector<int32_t> node0_children{1, 2};
+  node0.child_count = node0_children.size();
+  node0.children_in_traversal_order = node0_children.data();
+  node0.children_in_hit_test_order = node0_children.data();
+
+  // Add node 1: text child of node 0.
+  FlutterSemanticsNode node1{sizeof(FlutterSemanticsNode), 1};
+  node1.label = "prefecture";
+  node1.value = "Kyoto";
+
+  // Add node 2: subtree child of node 0.
+  FlutterSemanticsNode node2{sizeof(FlutterSemanticsNode), 2};
+  std::vector<int32_t> node2_children{3, 4};
+  node2.child_count = node2_children.size();
+  node2.children_in_traversal_order = node2_children.data();
+  node2.children_in_hit_test_order = node2_children.data();
+
+  // Add node 3: text child of node 2.
+  FlutterSemanticsNode node3{sizeof(FlutterSemanticsNode), 3};
+  node3.label = "city";
+  node3.value = "Uji";
+
+  // Add node 4: text child (with no text) of node 2.
+  FlutterSemanticsNode node4{sizeof(FlutterSemanticsNode), 4};
+
+  bridge->AddFlutterSemanticsNodeUpdate(&node0);
+  bridge->AddFlutterSemanticsNodeUpdate(&node1);
+  bridge->AddFlutterSemanticsNodeUpdate(&node2);
+  bridge->AddFlutterSemanticsNodeUpdate(&node3);
+  bridge->AddFlutterSemanticsNodeUpdate(&node4);
+  bridge->CommitUpdates();
+}
+
+}  // namespace
+
+TEST(AccessibilityBridgeDelegateWin32, DispatchAccessibilityAction) {
+  auto window_binding_handler =
+      std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>();
+  FlutterWindowsView view(std::move(window_binding_handler));
+  view.SetEngine(GetTestEngine());
+  view.OnUpdateSemanticsEnabled(true);
+
+  auto bridge = view.GetEngine()->accessibility_bridge().lock();
+  PopulateAXTree(bridge);
+
+  FlutterSemanticsAction actual_action = kFlutterSemanticsActionTap;
+  EngineModifier modifier(view.GetEngine());
+  modifier.embedder_api().DispatchSemanticsAction = MOCK_ENGINE_PROC(
+      DispatchSemanticsAction,
+      ([&actual_action](FLUTTER_API_SYMBOL(FlutterEngine) engine, uint64_t id,
+                        FlutterSemanticsAction action, const uint8_t* data,
+                        size_t data_length) {
+        actual_action = action;
+        return kSuccess;
+      }));
+
+  AccessibilityBridgeDelegateWin32 delegate(view.GetEngine());
+  delegate.DispatchAccessibilityAction(1, kFlutterSemanticsActionCopy, {});
+  EXPECT_EQ(actual_action, kFlutterSemanticsActionCopy);
+}
+
+}  // namespace testing
+}  // namespace flutter