Split NTPLoginHandler across chrome://apps and chrome://history.

chrome/browser/ui/webui/history_login_handler.h

+// Copyright 2015 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_HISTORY_LOGIN_HANDLER_H_
+#define CHROME_BROWSER_UI_WEBUI_HISTORY_LOGIN_HANDLER_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/public/browser/web_ui_message_handler.h"
+
+class ProfileInfoWatcher;
+
+// The handler for login-related messages from chrome://history.
+class HistoryLoginHandler : public content::WebUIMessageHandler {
+ public:
+  HistoryLoginHandler();
+  ~HistoryLoginHandler() override;
+
+  // WebUIMessageHandler implementation.
+  void RegisterMessages() override;
+
+ private:
+  // Handler for the "otherDevicesInitialized" message. No args.
+  void HandleOtherDevicesInitialized(const base::ListValue* args);
+
+  // Called by |profile_info_watcher_| on desktop if profile info changes.
+  void ProfileInfoChanged();
+
+  // Watches this web UI's profile for info changes (e.g. authenticated username
+  // changes).
+  scoped_ptr<ProfileInfoWatcher> profile_info_watcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(HistoryLoginHandler);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_HISTORY_LOGIN_HANDLER_H_