Adding JS and C++ handlers for events on new Welcome page.

chrome/browser/ui/webui/welcome_handler.h

+// Copyright 2016 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_WELCOME_HANDLER_H_
+#define CHROME_BROWSER_UI_WEBUI_WELCOME_HANDLER_H_
+
+#include "base/macros.h"
+#include "content/public/browser/web_ui_message_handler.h"
+#include "google_apis/gaia/oauth2_token_service.h"
+
+class Browser;
+class Profile;
+class ProfileOAuth2TokenService;
+
+// Handles actions on Welcome page.
+class WelcomeHandler : public content::WebUIMessageHandler,
+                       public OAuth2TokenService::Observer {
+ public:
+  explicit WelcomeHandler(content::WebUI* web_ui);
+  ~WelcomeHandler() override;
+
+  // OAuth2TokenService::Observer:
+  void OnRefreshTokenAvailable(const std::string& account_id) override;
+
+  // content::WebUIMessageHandler:
+  void RegisterMessages() override;
+
+ private:
+  enum WelcomeResult {
+    DEFAULT = 0,
+    SIGNED_IN,  // User clicked the "Sign In" button and completed sign-in.
+    DECLINED    // User clicked the "No Thanks" button.
+  };
+
+  void HandleActivateSignIn(const base::ListValue* args);
+  void HandleUserDecline(const base::ListValue* args);
+  void GoToNewTabPage();
+
+  Profile* profile_;
+  Browser* browser_;
+  ProfileOAuth2TokenService* oauth2_token_service_;
+  WelcomeResult result_;
+
+  DISALLOW_COPY_AND_ASSIGN(WelcomeHandler);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_WELCOME_HANDLER_H_