[Md Feedback] Add initial data population for dialog.

chrome/browser/ui/webui/md_feedback/md_feedback_webui_message_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_MD_FEEDBACK_MD_FEEDBACK_WEBUI_MESSAGE_HANDLER_H_
+#define CHROME_BROWSER_UI_WEBUI_MD_FEEDBACK_MD_FEEDBACK_WEBUI_MESSAGE_HANDLER_H_
+
+#include "base/macros.h"
+#include "content/public/browser/web_ui_message_handler.h"
+
+class MdFeedbackUI;
+
+// The handler for Javascript messages related to the feedback dialog.
+class MdFeedbackWebUIMessageHandler : public content::WebUIMessageHandler {
+ public:
+  explicit MdFeedbackWebUIMessageHandler(MdFeedbackUI* md_feedback_ui);
+  ~MdFeedbackWebUIMessageHandler() override;
+
+ private:
+  // WebUIMessageHandler:
+  void RegisterMessages() override;
+
+  // Handler for a JavaScript message that retrieves data (e.g. user email) to
+  // populate the feedback form.
+  void OnRequestData(const base::ListValue* args);
+
+  MdFeedbackUI* md_feedback_ui_;  // Not owned.
+
+  DISALLOW_COPY_AND_ASSIGN(MdFeedbackWebUIMessageHandler);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_MD_FEEDBACK_MD_FEEDBACK_WEBUI_MESSAGE_HANDLER_H_