[Device Discovery] Make DialRegistry a Singleton

chrome/browser/media/router/discovery/dial/dial_registry.cc

Index: chrome/browser/media/router/discovery/dial/dial_registry.cc
diff --git a/chrome/browser/media/router/discovery/dial/dial_registry.cc b/chrome/browser/media/router/discovery/dial/dial_registry.cc
index 11def8ff1deac094bedd6abe13b14adcac4f6c08..604093206fa51b76d0e1a3da19d161c80b3dd85f 100644
--- a/chrome/browser/media/router/discovery/dial/dial_registry.cc
+++ b/chrome/browser/media/router/discovery/dial/dial_registry.cc
@@ -24,28 +24,46 @@ using base::TimeDelta;
 using content::BrowserThread;
 using net::NetworkChangeNotifier;
 
+namespace {
+
+// How often to poll for devices.
+const int kDialRefreshIntervalSecs = 120;
+
+// We prune a device if it does not respond after this time.
+const int kDialExpirationSecs = 240;
+
+// The maximum number of devices retained at once in the registry.
+const size_t kDialMaxDevices = 256;
+
+}  // namespace
+
 namespace media_router {
 
-DialRegistry::DialRegistry(base::TimeDelta refresh_interval,
-                           base::TimeDelta expiration,
-                           const size_t max_devices)
+DialRegistry::DialRegistry()
     : num_listeners_(0),
       registry_generation_(0),
       last_event_registry_generation_(0),
       label_count_(0),
-      refresh_interval_delta_(refresh_interval),
-      expiration_delta_(expiration),
-      max_devices_(max_devices) {
+      refresh_interval_delta_(
+          base::TimeDelta::FromSeconds(kDialRefreshIntervalSecs)),
+      expiration_delta_(base::TimeDelta::FromSeconds(kDialExpirationSecs)),
+      max_devices_(kDialMaxDevices) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK_GT(max_devices_, 0U);
   NetworkChangeNotifier::AddNetworkChangeObserver(this);
 }
 
 DialRegistry::~DialRegistry() {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  // Singleton is destroyed on main thread.
   NetworkChangeNotifier::RemoveNetworkChangeObserver(this);
 }
 
+// static
+DialRegistry* DialRegistry::GetInstance() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  return base::Singleton<DialRegistry>::get();
+}
+
 std::unique_ptr<DialService> DialRegistry::CreateDialService() {
   DCHECK(g_browser_process->net_log());
   return base::MakeUnique<DialServiceImpl>(g_browser_process->net_log());
@@ -154,8 +172,9 @@ void DialRegistry::StartPeriodicDiscovery() {
   dial_ = CreateDialService();
   dial_->AddObserver(this);
   DoDiscovery();
-  repeating_timer_.Start(FROM_HERE, refresh_interval_delta_, this,
-                         &DialRegistry::DoDiscovery);
+  repeating_timer_.reset(new base::RepeatingTimer());
+  repeating_timer_->Start(FROM_HERE, refresh_interval_delta_, this,
+                          &DialRegistry::DoDiscovery);
 }
 
 void DialRegistry::DoDiscovery() {
@@ -170,7 +189,8 @@ void DialRegistry::StopPeriodicDiscovery() {
   if (!dial_)
     return;
 
-  repeating_timer_.Stop();
+  repeating_timer_->Stop();
+  repeating_timer_.reset();

[mark a. foltz, 2017/03/22 18:37:25]

Thanks for cleaning this up :)

   dial_->RemoveObserver(this);
   ClearDialService();
 }