[Media Router] Parse device description xml in utility process

chrome/browser/media/router/discovery/dial/safe_dial_device_description_parser.h

+// 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.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_SAFE_DIAL_DEVICE_DESCRIPTION_PARSER_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_SAFE_DIAL_DEVICE_DESCRIPTION_PARSER_H_
+
+#include <memory>
+#include <string>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/optional.h"
+#include "base/threading/thread_checker.h"
+#include "chrome/common/media_router/dial_device_description.h"
+#include "chrome/common/media_router/dial_device_description_parser.mojom.h"
+#include "content/public/browser/utility_process_mojo_client.h"
+
+namespace media_router {
+
+// SafeDialDeviceDescriptionParser parses the given device description XML file
+// safely via a utility process. This class runs on IO thread.
+class SafeDialDeviceDescriptionParser {
+ public:
+  // Callback function to be invoked when utility process finishes parsing
+  // device description XML.
+  // |success|: returns false if parsing fails.
+  // |device_description|: device description object. Empty if parsing fails.
+  using DeviceDescriptionCallback = base::Callback<void(
+      bool success,
+      const base::Optional<media_router::DialDeviceDescription>&
+          device_description)>;
+
+  SafeDialDeviceDescriptionParser();
+
+  // Start parsing device description XML file in utility process.
+  void Start(const std::string& xml_text,
+             const DeviceDescriptionCallback& callback);
+
+ private:
+  ~SafeDialDeviceDescriptionParser();
+
+  // See SafeDialDeviceDescriptionParser::DeviceDescriptionCallback
+  void OnParseDeviceDescriptionComplete(
+      bool success,
+      const base::Optional<media_router::DialDeviceDescription>&
+          device_description);
+
+  // TODO(crbug.com/702766): Add an enum type describing why utility process
+  // fails to parse device description xml.
+  void OnParseDeviceDescriptionFailed();
+
+  // Utility client used to send device description parsing task to the utility
+  // process.
+  std::unique_ptr<content::UtilityProcessMojoClient<
+      chrome::mojom::DialDeviceDescriptionParser>>
+      utility_process_mojo_client_;
+
+  // Only accessed on the IO thread.
+  DeviceDescriptionCallback device_description_callback_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(SafeDialDeviceDescriptionParser);
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_SAFE_DIAL_DEVICE_DESCRIPTION_PARSER_H_