Adds QueryResultManager support class for Media Router Dialog WebUI

chrome/browser/ui/webui/media_router/query_result_manager.cc

+// Copyright 2015 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/ui/webui/media_router/query_result_manager.h"
+
+#include <unordered_set>
+
+#include "base/stl_util.h"
+#include "chrome/browser/media/router/media_router.h"
+#include "chrome/browser/media/router/media_sinks_observer.h"
+
+namespace media_router {
+
+// MediaSinkObserver that propagates results back to |result_manager|.
+// An instance of this class is associated with each registered MediaCastMode.
+class CastModeMediaSinksObserver : public MediaSinksObserver {
+ public:
+  CastModeMediaSinksObserver(MediaCastMode cast_mode,
+                             const MediaSource& source,
+                             MediaRouter* router,
+                             QueryResultManager* result_manager)
+      : MediaSinksObserver(router, source),
+        cast_mode_(cast_mode),
+        result_manager_(result_manager) {
+    DCHECK(result_manager);
+  }
+
+  ~CastModeMediaSinksObserver() override {}
+
+  // MediaSinksObserver
+  void OnSinksReceived(const std::vector<MediaSink>& result) override {
+    latest_sink_ids_.clear();
+    for (const MediaSink& sink : result) {
+      latest_sink_ids_.push_back(sink.id());
+    }
+    result_manager_->UpdateWithSinksQueryResult(cast_mode_, result);
+    result_manager_->NotifyOnResultsUpdated();
+  }
+
+  // Returns the most recent sink IDs that were passed to |OnSinksReceived|.
+  void GetLatestSinkIds(std::vector<MediaSinkId>* sink_ids) const {
+    DCHECK(sink_ids);
+    *sink_ids = latest_sink_ids_;
+  }
+
+  MediaCastMode cast_mode() const { return cast_mode_; }
+
+ private:
+  MediaCastMode cast_mode_;
+  std::vector<MediaSinkId> latest_sink_ids_;
+  QueryResultManager* result_manager_;
+};
+
+QueryResultManager::QueryResultManager(MediaRouter* router) : router_(router) {
+  DCHECK(router_);
+}
+
+QueryResultManager::~QueryResultManager() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void QueryResultManager::AddObserver(Observer* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(observer);
+  observers_.AddObserver(observer);
+}
+
+void QueryResultManager::RemoveObserver(Observer* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(observer);
+  observers_.RemoveObserver(observer);
+}
+
+void QueryResultManager::StartSinksQuery(MediaCastMode cast_mode,
+                                         const MediaSource& source) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (source.Empty()) {
+    LOG(WARNING) << "StartSinksQuery called with empty source for "
+                 << cast_mode;
+    return;
+  }
+
+  SetSourceForCastMode(cast_mode, source);
+  RemoveObserverForCastMode(cast_mode);
+  UpdateWithSinksQueryResult(cast_mode, std::vector<MediaSink>());
+
+  linked_ptr<CastModeMediaSinksObserver> observer(
+      new CastModeMediaSinksObserver(cast_mode, source, router_, this));
+  auto result = sinks_observers_.insert(std::make_pair(cast_mode, observer));
+  DCHECK(result.second);
+  NotifyOnResultsUpdated();
+}
+
+void QueryResultManager::StopSinksQuery(MediaCastMode cast_mode) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  RemoveObserverForCastMode(cast_mode);
+  SetSourceForCastMode(cast_mode, MediaSource());
+  UpdateWithSinksQueryResult(cast_mode, std::vector<MediaSink>());
+  NotifyOnResultsUpdated();
+}
+
+void QueryResultManager::SetSourceForCastMode(
+      MediaCastMode cast_mode, const MediaSource& source) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  cast_mode_sources_[cast_mode] = source;
+}
+
+void QueryResultManager::RemoveObserverForCastMode(MediaCastMode cast_mode) {
+  auto observers_it = sinks_observers_.find(cast_mode);
+  if (observers_it != sinks_observers_.end())
+    sinks_observers_.erase(observers_it);
+}
+
+bool QueryResultManager::IsValid(const MediaSinkWithCastModes& entry) const {
+  return !entry.cast_modes.empty();
+}
+
+void QueryResultManager::UpdateWithSinksQueryResult(
+    MediaCastMode cast_mode,
+    const std::vector<MediaSink>& result) {
+  std::unordered_set<MediaSinkId> result_sink_ids;
+  for (const MediaSink& sink : result)
+    result_sink_ids.insert(sink.id());
+
+  // (1) Iterate through current sink set, remove cast mode from those that
+  // do not appear in latest result.
+  for (auto it = all_sinks_.begin(); it != all_sinks_.end(); /*no-op*/) {
+    if (!ContainsKey(result_sink_ids, it->first)) {
+      it->second.cast_modes.erase(cast_mode);
+    }
+    if (!IsValid(it->second)) {
+      all_sinks_.erase(it++);
+    } else {
+      ++it;
+    }
+  }
+
+  // (2) Add / update sinks with latest result.
+  for (const MediaSink& sink : result) {
+    auto result =
+      all_sinks_.insert(std::make_pair(sink.id(),
+                                       MediaSinkWithCastModes(sink)));
+    if (!result.second)
+      result.first->second.sink = sink;

[Bernhard Bauer, 2015/05/12 09:34:34]

Thinking about this a bit more, even if we have not inserted a new entry, this
is basically guaranteed by the invariant, right? Should we just DCHECK it?

[mark a. foltz, 2015/05/12 19:05:26]

If there's an existing sink in all_sinks_ it's not guaranteed to be identical to
|sink|.  For example the user might have renamed their Chromecast between calls
to UpdateWithSinksQueryResult().  It's a bit of a corner case but I'd rather
ensure we have the latest version.

[Bernhard Bauer, 2015/05/13 08:04:24]

Okay, makes sense.

+    result.first->second.cast_modes.insert(cast_mode);
+  }
+}
+
+void QueryResultManager::GetSupportedCastModes(CastModeSet* cast_modes) const {
+  DCHECK(cast_modes);
+  cast_modes->clear();
+  for (const auto& observer_pair : sinks_observers_) {
+    cast_modes->insert(observer_pair.first);
+  }
+}
+
+MediaSource QueryResultManager::GetSourceForCastMode(
+      MediaCastMode cast_mode) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  auto source_it = cast_mode_sources_.find(cast_mode);
+  if (source_it == cast_mode_sources_.end())
+    return MediaSource();
+  return source_it->second;
+}
+
+void QueryResultManager::NotifyOnResultsUpdated() {
+  std::vector<MediaSinkWithCastModes> sinks;
+  for (const auto& sink_pair : all_sinks_) {
+    sinks.push_back(sink_pair.second);
+  }
+  FOR_EACH_OBSERVER(QueryResultManager::Observer, observers_,
+      OnResultsUpdated(sinks));
+}
+
+}  // namespace media_router