[fuchsia] Register Views with Fuchsia Accessibility APIs

* Add the AccessibilityBridge class skeleton, which will eventually
handle the logic for conversion between Chromium and Fuchsia
accessibility data structures.
* Register a ViewRef to the Fuchsia SemanticsManager.

Test: Added AccessibilityBridgeUnitTest.*

Bug: 973095
Change-Id: Ie8eb6a8cdd68e0082d3479b9b1288f8aaa68a600
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1708043
Commit-Queue: Sharon Yang <yangsharon@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693914}

fuchsia/engine/BUILD.gn

@@ -85,6 +85,8 @@ component("web_engine_core") {
     "//services/service_manager/sandbox",
     "//skia/public/mojom",
     "//third_party/blink/public/common",
+    "//third_party/fuchsia-sdk/sdk:accessibility_semantics",
+    "//third_party/fuchsia-sdk/sdk:math",
     "//third_party/fuchsia-sdk/sdk:scenic_cpp",
     "//third_party/fuchsia-sdk/sdk:sys_cpp",
     "//third_party/fuchsia-sdk/sdk:web",
@@ -109,6 +111,8 @@ component("web_engine_core") {
   ]
   configs += [ ":web_engine_implementation" ]
   sources = [
+    "browser/accessibility_bridge.cc",
+    "browser/accessibility_bridge.h",
     "browser/content_directory_loader_factory.cc",
     "browser/content_directory_loader_factory.h",
     "browser/context_impl.cc",
@@ -240,6 +244,7 @@ test("web_engine_browsertests") {
 
 test("web_engine_unittests") {
   sources = [
+    "browser/accessibility_bridge_unittest.cc",
     "browser/cookie_manager_impl_unittest.cc",
     "browser/frame_impl_unittest.cc",
     "context_provider_impl_unittest.cc",
@@ -256,6 +261,7 @@ test("web_engine_unittests") {
     "//services/network/public/mojom",
     "//testing/gmock",
     "//testing/gtest",
+    "//third_party/fuchsia-sdk/sdk:scenic_cpp",
     "//third_party/fuchsia-sdk/sdk:web",
   ]
 }

fuchsia/engine/browser/accessibility_bridge.cc

+// Copyright 2019 The Chromium 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 "fuchsia/engine/browser/accessibility_bridge.h"
+
+#include "base/logging.h"
+
+AccessibilityBridge::AccessibilityBridge(
+    fuchsia::accessibility::semantics::SemanticsManagerPtr semantics_manager,
+    fuchsia::ui::views::ViewRef view_ref)
+    : binding_(this) {
+  semantics_manager->RegisterViewForSemantics(
+      std::move(view_ref), binding_.NewBinding(), tree_ptr_.NewRequest());
+}
+
+AccessibilityBridge::~AccessibilityBridge() = default;
+
+void AccessibilityBridge::OnAccessibilityActionRequested(
+    uint32_t node_id,
+    fuchsia::accessibility::semantics::Action action,
+    OnAccessibilityActionRequestedCallback callback) {
+  NOTIMPLEMENTED();
+}
+
+void AccessibilityBridge::HitTest(fuchsia::math::PointF local_point,
+                                  HitTestCallback callback) {
+  NOTIMPLEMENTED();
+}
+
+void AccessibilityBridge::OnSemanticsModeChanged(
+    bool updates_enabled,
+    OnSemanticsModeChangedCallback callback) {
+  NOTIMPLEMENTED();
+}

fuchsia/engine/browser/accessibility_bridge.h

+// Copyright 2019 The Chromium 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 FUCHSIA_ENGINE_BROWSER_ACCESSIBILITY_BRIDGE_H_
+#define FUCHSIA_ENGINE_BROWSER_ACCESSIBILITY_BRIDGE_H_
+
+#include <fuchsia/accessibility/semantics/cpp/fidl.h>
+#include <fuchsia/math/cpp/fidl.h>
+#include <fuchsia/ui/views/cpp/fidl.h>
+#include <lib/fidl/cpp/binding.h>
+
+#include "base/macros.h"
+
+// This class is the intermediate for accessibility between Chrome and Fuchsia.
+// It handles registration to the Fuchsia Semantics Manager, translating events
+// and data structures between the two services, and forwarding actions and
+// events.
+// The lifetime of an instance of AccessibilityBridge is the same as that of a
+// View created by FrameImpl. This class refers to the View via the
+// caller-supplied ViewRef.
+class AccessibilityBridge
+    : public fuchsia::accessibility::semantics::SemanticListener {
+ public:
+  AccessibilityBridge(
+      fuchsia::accessibility::semantics::SemanticsManagerPtr semantics_manager,
+      fuchsia::ui::views::ViewRef view_ref);
+  ~AccessibilityBridge() final;
+
+ private:
+  // fuchsia::accessibility::semantics::SemanticListener implementation.
+  void OnAccessibilityActionRequested(
+      uint32_t node_id,
+      fuchsia::accessibility::semantics::Action action,
+      OnAccessibilityActionRequestedCallback callback) final;
+  void HitTest(fuchsia::math::PointF local_point,
+               HitTestCallback callback) final;
+  void OnSemanticsModeChanged(bool updates_enabled,
+                              OnSemanticsModeChangedCallback callback) final;
+
+  fuchsia::accessibility::semantics::SemanticTreePtr tree_ptr_;
+  fidl::Binding<fuchsia::accessibility::semantics::SemanticListener> binding_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccessibilityBridge);
+};
+
+#endif  // FUCHSIA_ENGINE_BROWSER_ACCESSIBILITY_BRIDGE_H_

fuchsia/engine/browser/accessibility_bridge_unittest.cc

+// Copyright 2019 The Chromium 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 "fuchsia/engine/browser/accessibility_bridge.h"
+
+#include <fuchsia/accessibility/semantics/cpp/fidl.h>
+#include <fuchsia/accessibility/semantics/cpp/fidl_test_base.h>
+#include <lib/sys/cpp/component_context.h>
+#include <lib/ui/scenic/cpp/view_ref_pair.h>
+#include <zircon/types.h>
+
+#include "base/fuchsia/default_context.h"
+#include "base/fuchsia/scoped_service_binding.h"
+#include "base/fuchsia/service_directory_client.h"
+#include "base/logging.h"
+#include "base/test/task_environment.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using fuchsia::accessibility::semantics::SemanticListener;
+using fuchsia::accessibility::semantics::SemanticsManager;
+
+namespace {
+
+class FakeSemanticsManager : public fuchsia::accessibility::semantics::testing::
+                                 SemanticsManager_TestBase {
+ public:
+  explicit FakeSemanticsManager() = default;
+  ~FakeSemanticsManager() override = default;
+
+  // fuchsia::accessibility::semantics::SemanticsManager implementation.
+  void RegisterViewForSemantics(
+      fuchsia::ui::views::ViewRef view_ref,
+      fidl::InterfaceHandle<SemanticListener> listener,
+      fidl::InterfaceRequest<fuchsia::accessibility::semantics::SemanticTree>
+          semantic_tree) final {
+    view_ref_ = std::move(view_ref);
+    listener_ = std::move(listener);
+    semantic_tree_ = std::move(semantic_tree);
+  }
+
+  bool is_view_registered() const { return view_ref_.reference.is_valid(); }
+
+  bool is_listener_handle_valid() const { return listener_.is_valid(); }
+
+  bool is_semantic_tree_handle_valid() const {
+    return semantic_tree_.is_valid();
+  }
+
+  void NotImplemented_(const std::string& name) final {
+    NOTIMPLEMENTED() << name;
+  }
+
+ private:
+  fuchsia::ui::views::ViewRef view_ref_;
+  fidl::InterfaceHandle<SemanticListener> listener_;
+  fidl::InterfaceRequest<fuchsia::accessibility::semantics::SemanticTree>
+      semantic_tree_;
+
+  DISALLOW_COPY_AND_ASSIGN(FakeSemanticsManager);
+};
+
+}  // namespace
+
+class AccessibilityBridgeTest : public testing::Test {
+ public:
+  AccessibilityBridgeTest()
+      : task_environment_(
+            base::test::ScopedTaskEnvironment::MainThreadType::IO),
+        semantics_manager_binding_(&semantics_manager_) {}
+  ~AccessibilityBridgeTest() override = default;
+
+  void CreateAccessibilityBridge() {
+    auto view_ref_pair = scenic::ViewRefPair::New();
+    control_ref_ = std::move(view_ref_pair.control_ref);
+    fuchsia::accessibility::semantics::SemanticsManagerPtr
+        semantics_manager_ptr;
+    semantics_manager_binding_.Bind(semantics_manager_ptr.NewRequest());
+    accessibility_bridge_ = std::make_unique<AccessibilityBridge>(
+        std::move(semantics_manager_ptr), std::move(view_ref_pair.view_ref));
+  }
+
+ protected:
+  base::test::SingleThreadTaskEnvironment task_environment_;
+  std::unique_ptr<AccessibilityBridge> accessibility_bridge_;
+  FakeSemanticsManager semantics_manager_;
+  fidl::Binding<fuchsia::accessibility::semantics::SemanticsManager>
+      semantics_manager_binding_;
+  fuchsia::ui::views::ViewRefControl control_ref_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccessibilityBridgeTest);
+};
+
+// Test registration to the SemanticsManager.
+TEST_F(AccessibilityBridgeTest, RegisterViewRef) {
+  CreateAccessibilityBridge();
+  // Run loop so FIDL registration requests are processed.
+  task_environment_.RunUntilIdle();
+  EXPECT_TRUE(semantics_manager_.is_view_registered());
+  EXPECT_TRUE(semantics_manager_.is_listener_handle_valid());
+  EXPECT_TRUE(semantics_manager_.is_semantic_tree_handle_valid());
+}