Add DiscoveryNetworkMonitor implementation

chrome/browser/media/router/discovery/discovery_network_monitor.cc

Index: chrome/browser/media/router/discovery/discovery_network_monitor.cc
diff --git a/chrome/browser/media/router/discovery/discovery_network_monitor.cc b/chrome/browser/media/router/discovery/discovery_network_monitor.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2b2b7606f1b95c0e43a2ccaaf56f21f365d8eec8
--- /dev/null
+++ b/chrome/browser/media/router/discovery/discovery_network_monitor.cc
@@ -0,0 +1,126 @@
+// Copyright (c) 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/discovery_network_monitor.h"
+
+#include <unordered_set>
+
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/sha1.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "chrome/browser/media/router/discovery/discovery_network_list.h"
+#include "net/base/network_interfaces.h"
+
+namespace {
+
+using content::BrowserThread;
+
+std::string ComputeNetworkId(
+    const std::vector<DiscoveryNetworkInfo>& network_info_list) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (network_info_list.size() == 0) {
+    return DiscoveryNetworkMonitor::kNetworkIdDisconnected;
+  }
+  if (std::find_if(network_info_list.begin(), network_info_list.end(),
+                   [](const DiscoveryNetworkInfo& network_info) {
+                     return network_info.network_id.size() > 0;
+                   }) == network_info_list.end()) {
+    return DiscoveryNetworkMonitor::kNetworkIdUnknown;
+  }
+
+  std::string combined_ids;
+  for (const auto& network_info : network_info_list) {
+    combined_ids = combined_ids + "!" + network_info.network_id;
+  }
+
+  std::string hash = base::SHA1HashString(combined_ids);
+  return base::ToLowerASCII(base::HexEncode(hash.data(), hash.length()));
+}
+
+std::vector<DiscoveryNetworkInfo> GetNetworkInfo() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  return GetDiscoveryNetworkInfoList();
+}
+
+base::LazyInstance<DiscoveryNetworkMonitor>::Leaky g_discovery_monitor;
+
+}  // namespace
+
+// static
+constexpr char const DiscoveryNetworkMonitor::kNetworkIdDisconnected[];
+// static
+constexpr char const DiscoveryNetworkMonitor::kNetworkIdUnknown[];
+
+// static
+DiscoveryNetworkMonitor* DiscoveryNetworkMonitor::GetInstance() {
+  return g_discovery_monitor.Pointer();
+}
+
+void DiscoveryNetworkMonitor::RebindNetworkChangeObserverForTest() {
+  net::NetworkChangeNotifier::AddNetworkChangeObserver(this);
+}
+
+void DiscoveryNetworkMonitor::SetNetworkInfoFunctionForTest(
+    NetworkInfoFunction strategy) {
+  network_info_function_ = strategy;
+}
+
+void DiscoveryNetworkMonitor::AddObserver(Observer* const observer) {
+  observers_->AddObserver(observer);
+}
+
+void DiscoveryNetworkMonitor::RemoveObserver(Observer* const observer) {
+  observers_->RemoveObserver(observer);
+}
+
+void DiscoveryNetworkMonitor::Refresh(NetworkRefreshCompleteCallback callback) {
+  BrowserThread::PostTaskAndReply(
+      BrowserThread::IO, FROM_HERE,
+      base::BindOnce(&DiscoveryNetworkMonitor::UpdateNetworkInfo,
+                     base::Unretained(this)),
+      std::move(callback));
+}
+
+const std::string& DiscoveryNetworkMonitor::GetNetworkId() const {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  return network_id_;
+}
+
+DiscoveryNetworkMonitor::DiscoveryNetworkMonitor()
+    : network_id_(kNetworkIdDisconnected),
+      observers_(new base::ObserverListThreadSafe<Observer>(
+          base::ObserverListThreadSafe<
+              Observer>::NotificationType::NOTIFY_EXISTING_ONLY)),
+      network_info_function_(&GetNetworkInfo) {
+  net::NetworkChangeNotifier::AddNetworkChangeObserver(this);
+}
+
+DiscoveryNetworkMonitor::~DiscoveryNetworkMonitor() {
+  net::NetworkChangeNotifier::RemoveNetworkChangeObserver(this);
+}
+
+void DiscoveryNetworkMonitor::OnNetworkChanged(
+    net::NetworkChangeNotifier::ConnectionType) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&DiscoveryNetworkMonitor::UpdateNetworkInfo,
+                 base::Unretained(this)));
+}
+
+void DiscoveryNetworkMonitor::UpdateNetworkInfo() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  auto network_info_list = network_info_function_();
+  auto network_id = ComputeNetworkId(network_info_list);
+
+  network_id_.swap(network_id);
+
+  if (network_id_ != network_id) {
+    observers_->Notify(FROM_HERE, &Observer::OnNetworksChanged,
+                       base::ConstRef(*this));
+  }
+}