[Media Router] Add DialMediaSinkService and DeviceDescriptionService

chrome/browser/media/router/discovery/dial/dial_media_sink_cache_service.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/browser/media/router/discovery/dial/dial_media_sink_cache_service.h"
+
+#include "base/time/time.h"
+
+using base::Time;
+using base::TimeDelta;
+
+namespace {
+// The maximum time a response is expected after a M-SEARCH request.
+const int kSinkAliveTimeoutSecs = 2 * 60;
+}
+
+namespace media_router {
+
+DialMediaSinkCacheService::DialMediaSinkCacheService() {}
+DialMediaSinkCacheService::~DialMediaSinkCacheService() {}
+
+std::vector<MediaSinkInternal> DialMediaSinkCacheService::GetAliveSinks() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  std::vector<MediaSinkInternal> alive_sinks;
+  for (const auto& sink_it : cached_sinks_) {
+    if (IsAlive(sink_it.second))
+      alive_sinks.push_back(sink_it.second.sink);
+  }
+  return alive_sinks;
+}
+
+void DialMediaSinkCacheService::MayAddOrUpdateSink(
+    const DialDeviceData& device_data,
+    const ParsedDialDeviceDescription& device_description) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  MediaSink sink(device_description.unique_id, device_description.friendly_name,
+                 MediaSink::IconType::CAST);

[imcheng, 2017/04/12 19:33:51]

Should IconType be GENERIC?

[zhaobin, 2017/04/18 06:58:27]

Done.

+  DialSinkExtraData extra_data;
+  extra_data.app_url = device_description.app_url;
+  extra_data.model_name = device_description.model_name;
+  DCHECK(extra_data.ip_address.AssignFromIPLiteral(

[mark a. foltz, 2017/04/12 00:17:18]

Does this need to run in release builds?

[zhaobin, 2017/04/18 06:58:27]

Yes. Changed to if.

+      device_data.device_description_url().host()));
+
+  CachedDialMediaSink cached_sink;
+  cached_sink.sink = MediaSinkInternal(sink, extra_data);
+  cached_sink.last_update_time = base::Time::Now();

[mark a. foltz, 2017/04/12 00:17:18]

Maybe it would be simpler to track a per-sink expiration time?

[zhaobin, 2017/04/18 06:58:27]

Done.

+
+  const auto& sink_it = cached_sinks_.find(sink.id());
+  if (sink_it == cached_sinks_.end()) {
+    cached_sinks_.insert(std::make_pair(sink.id(), cached_sink));
+    return;
+  }
+
+  sink_it->second = cached_sink;

[mark a. foltz, 2017/04/12 00:17:18]

Do you think it would be simpler to assign fields in sink_it->second, versus
having to create a cached_sink object to replace it, since not all of the fields
will change?

[zhaobin, 2017/04/18 06:58:27]

Done.

+}
+
+bool DialMediaSinkCacheService::IsAlive(const CachedDialMediaSink& sink) {

[imcheng, 2017/04/12 19:33:51]

It seems we never erase from cached_sinks_; should there be a periodic mechanism
to remove ones that are no longer accessible (e.g, by issuing a GET request and
checking if it succeeds) based on last_update_time?

[zhaobin, 2017/04/18 06:58:27]

I have removed all CheckAccess() related logic here to make this patch simple
(still quite large though)...Add a TODO for check access?

+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  return sink.last_update_time +
+             base::TimeDelta::FromSeconds(kSinkAliveTimeoutSecs) >
+         base::Time::Now();
+}
+
+}  // namespace media_router