[Media Router] Parse device description xml in utility process

chrome/browser/media/router/discovery/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_SAFE_DIAL_DEVICE_DESCRIPTION_PARSER_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_SAFE_DIAL_DEVICE_DESCRIPTION_PARSER_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "chrome/common/extensions/dial_device_description_parser.mojom.h"
+#include "chrome/common/media_router/dial_device_description.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 base::RefCountedThreadSafe<SafeDialDeviceDescriptionParser> {

[mark a. foltz, 2017/03/17 19:05:46]

If this is used *only* on the IO thread I think this can be base::RefCounted<>.

[zhaobin, 2017/03/18 00:17:38]

Done.

+ public:
+  using DeviceDescriptionCallback =

[mark a. foltz, 2017/03/17 19:05:46]

Document the parameters here (especially the first and third)

[zhaobin, 2017/03/18 00:17:38]

Done.

+      base::Callback<void(bool,
+                          const media_router::DialDeviceDescription&,
+                          const std::string&)>;
+
+  SafeDialDeviceDescriptionParser();
+
+  // Start parsing device description XML file in utility process.
+  void Start(const std::string& xml_text,
+             const DeviceDescriptionCallback& callback);
+
+ private:
+  friend class base::RefCountedThreadSafe<SafeDialDeviceDescriptionParser>;
+
+  ~SafeDialDeviceDescriptionParser();
+
+  // Notification from the utility process when it finishes parsing the
+  // device description XML. Runs on IO thread.

[mark a. foltz, 2017/03/17 19:05:46]

Please document the meanings of |result| and |logging_xml|

[zhaobin, 2017/03/18 00:17:38]

Done.

+  void ParseDialDeviceDescriptionDone(
+      bool result,
+      const media_router::DialDeviceDescription& device_description,
+      const std::string& logging_xml);
+
+  void ParseDialDeviceDescriptionFailed();

[mark a. foltz, 2017/03/17 19:05:46]

Can this take an enum describing the reason why it failed?  We will probably
want to add an UMA histogram tracking failure reasons.

(Fine to add as a TODO() for later).

[zhaobin, 2017/03/18 00:17:38]

Done.

+
+  // Utility client used to send device description parsing task to the utility
+  // process.
+  std::unique_ptr<content::UtilityProcessMojoClient<
+      extensions::mojom::DialDeviceDescriptionParser>>
+      utility_process_mojo_client_;
+
+  // Only accessed on the IO thread.
+  DeviceDescriptionCallback device_description_callback_;
+

[mark a. foltz, 2017/03/17 19:05:46]

Add a base::ThreadChecker to enforce thread safety.

[zhaobin, 2017/03/18 00:17:38]

Done.

+  DISALLOW_COPY_AND_ASSIGN(SafeDialDeviceDescriptionParser);
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_SAFE_DIAL_DEVICE_DESCRIPTION_PARSER_H_