[Media Router] Parse device description xml in utility process

chrome/utility/media_router/dial_device_description_parser_impl.cc

+// 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.
+
+#include "chrome/utility/media_router/dial_device_description_parser_impl.h"
+
+#include <libxml/parser.h>
+#include <libxml/tree.h>
+#include <libxml/xpath.h>
+
+#include "base/strings/stringprintf.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "third_party/libxml/chromium/libxml_utils.h"
+
+namespace {
+
+std::string Validate(const media_router::DialDeviceDescription& description) {
+  if (description.unique_id.empty()) {
+    return "Missing uniqueId";
+  }
+  if (description.friendly_name.empty()) {
+    return "Missing friendlyName";
+  }
+  return "";

[dcheng, 2017/03/22 09:53:02]

Nit: return std::string()

[zhaobin, 2017/03/22 19:18:52]

Done.

+}
+
+// If friendly name does not exist, fall back to use model name + last 4
+// digits of UUID as friendly name.
+void ComputeFriendlyName(media_router::DialDeviceDescription* out) {
+  auto model_name = out->model_name;

[dcheng, 2017/03/22 09:53:02]

nit: const auto& to avoid a copy (same below)

[zhaobin, 2017/03/22 19:18:52]

Done.

+  auto unique_id = out->unique_id;
+
+  if (model_name.empty() || unique_id.length() < 4)
+    return;
+
+  std::string trimmed_unique_id = unique_id.substr(unique_id.length() - 4);
+  out->friendly_name = base::StringPrintf("%s [%s]", model_name.c_str(),
+                                          trimmed_unique_id.c_str());
+}
+
+}  // namespace
+
+namespace media_router {
+
+DialDeviceDescriptionParserImpl::DialDeviceDescriptionParserImpl() = default;
+DialDeviceDescriptionParserImpl::~DialDeviceDescriptionParserImpl() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+// static
+void DialDeviceDescriptionParserImpl::Create(
+    chrome::mojom::DialDeviceDescriptionParserRequest request) {
+  mojo::MakeStrongBinding(base::MakeUnique<DialDeviceDescriptionParserImpl>(),

[dcheng, 2017/03/22 09:53:02]

#include "base/memory/ptr_util.h" for MakeUnique

[zhaobin, 2017/03/22 19:18:52]

Done.

+                          std::move(request));

[dcheng, 2017/03/22 09:53:02]

Nit: #include <utility>

[zhaobin, 2017/03/22 19:18:52]

Done.

+}
+
+void DialDeviceDescriptionParserImpl::ParseDialDeviceDescription(
+    const std::string& device_description_xml_data,
+    const ParseDialDeviceDescriptionCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!callback.is_null());
+
+  media_router::DialDeviceDescription device_description;
+  bool result = Parse(device_description_xml_data, &device_description);
+
+  if (result) {
+    callback.Run(result, device_description);
+  } else {
+    callback.Run(result, base::nullopt);
+  }
+}
+
+bool DialDeviceDescriptionParserImpl::Parse(
+    const std::string& xml,
+    media_router::DialDeviceDescription* out) {
+  DCHECK(out);
+
+  XmlReader xml_reader;
+  if (!xml_reader.Load(xml))
+    return false;
+
+  while (xml_reader.Read()) {
+    xml_reader.SkipToElement();
+    std::string node_name(xml_reader.NodeName());
+
+    if (node_name == "UDN") {
+      if (!xml_reader.ReadElementContent(&out->unique_id))
+        return false;
+    } else if (node_name == "friendlyName") {
+      if (!xml_reader.ReadElementContent(&out->friendly_name))
+        return false;
+    } else if (node_name == "modelName") {
+      if (!xml_reader.ReadElementContent(&out->model_name))
+        return false;
+    } else if (node_name == "deviceType") {
+      if (!xml_reader.ReadElementContent(&out->device_type))
+        return false;
+    }
+  }
+
+  if (out->friendly_name.empty())
+    ComputeFriendlyName(out);
+
+  std::string error = Validate(*out);

[dcheng, 2017/03/22 09:53:02]

Will this string eventually be returned to the user? If not, I'd suggest using
an enum (the string itself probably won't be optimized out)

[zhaobin, 2017/03/22 19:18:52]

Done.

+  if (!error.empty()) {
+    DLOG(WARNING) << "Device description failed to validate: " << error;
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace media_router