Set keys to traverse accessibility tree. Using focus ring to highlight selected node.

chrome/browser/chromeos/accessibility/event_handler_common.cc

+// Copyright 2017 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 "chrome/browser/chromeos/accessibility/event_handler_common.h"
+
+#include "chrome/browser/chromeos/accessibility/accessibility_manager.h"
+#include "chrome/browser/profiles/profile_manager.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_widget_host.h"
+#include "extensions/browser/extension_host.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/browser/process_manager.h"
+
+namespace chromeos {
+
+extensions::ExtensionHost* GetAccessibilityExtensionHost(
+    const std::string& extension_id) {
+  if (!AccessibilityManager::Get())
+    return nullptr;
+
+  content::BrowserContext* context = ProfileManager::GetActiveUserProfile();
+  if (!context)
+    return nullptr;
+
+  const extensions::Extension* extension =
+      extensions::ExtensionRegistry::Get(context)->enabled_extensions().GetByID(
+          extension_id);
+  if (!extension)
+    return nullptr;
+
+  extensions::ExtensionHost* host =
+      extensions::ProcessManager::Get(context)->GetBackgroundHostForExtension(
+          extension->id());
+  return host;
+}
+
+void ForwardKeyToExtension(const ui::KeyEvent& key_event,
+                           extensions::ExtensionHost* host) {
+  if (!host) {
+    LOG(ERROR) << "Unable to forward key to extension";
+    return;
+  }
+
+  content::RenderViewHost* rvh = host->render_view_host();
+  if (!rvh) {
+    LOG(ERROR) << "Unable to forward key to extension";
+    return;
+  }
+
+  const content::NativeWebKeyboardEvent web_event(key_event);
+  rvh->GetWidget()->ForwardKeyboardEvent(web_event);
+}
+}  // namespace chromeos