diff --git a/chrome/browser/ui/webui/components_handler.h b/chrome/browser/ui/webui/components_handler.h
new file mode 100644
index 0000000..a17d69a
--- /dev/null
+++ b/chrome/browser/ui/webui/components_handler.h
@@ -0,0 +1,54 @@
+// 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 CHROME_BROWSER_UI_WEBUI_COMPONENTS_HANDLER_H_
+#define CHROME_BROWSER_UI_WEBUI_COMPONENTS_HANDLER_H_
+
+#include <memory>
+#include <string>
+
+#include "base/strings/string16.h"
+#include "components/component_updater/component_updater_service.h"
+#include "components/update_client/update_client.h"
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/web_ui_message_handler.h"
+
+namespace base {
+class ListValue;
+}
+
+// The handler for Javascript messages for the chrome://components/ page.
+class ComponentsHandler : public content::WebUIMessageHandler,
+                          public component_updater::ServiceObserver {
+ public:
+  ComponentsHandler();
+  ComponentsHandler(const ComponentsHandler&) = delete;
+  ComponentsHandler& operator=(const ComponentsHandler&) = delete;
+  ~ComponentsHandler() override;
+
+  // WebUIMessageHandler implementation.
+  void RegisterMessages() override;
+  void OnJavascriptAllowed() override;
+  void OnJavascriptDisallowed() override;
+
+  // Callback for the "requestComponentsData" message.
+  void HandleRequestComponentsData(const base::ListValue* args);
+
+  // Callback for the "checkUpdate" message.
+  void HandleCheckUpdate(const base::ListValue* args);
+
+  // ServiceObserver implementation.
+  void OnEvent(Events event, const std::string& id) override;
+
+ private:
+  static base::string16 ComponentEventToString(Events event);
+  static base::string16 ServiceStatusToString(
+      update_client::ComponentState state);
+  static std::unique_ptr<base::ListValue> LoadComponents();
+  static void OnDemandUpdate(const std::string& component_id);
+
+  content::NotificationRegistrar registrar_;
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_COMPONENTS_HANDLER_H_