Always stop PrivetTrafficDetector.

Currently, there are some code paths in PrivetNotificationService where
PrivetTrafficDetector is not stopped. This causes PrivetTrafficDetector
to forget to unregister itself from NetworkConnectionTracker.

BUG=866199

Change-Id: I75721603889a6886b012d439bd6e8f2266083ee1
Reviewed-on: https://chromium-review.googlesource.com/1145888Reviewed-by: Robbie McElrath <rmcelrath@chromium.org>
Reviewed-by: Helen Li <xunjieli@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577220}

chrome/browser/printing/cloud_print/privet_notifications.cc

@@ -209,8 +209,8 @@ PrivetNotificationService::PrivetNotificationService(
 }
 
 PrivetNotificationService::~PrivetNotificationService() {
-#if BUILDFLAG(ENABLE_MDNS)
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+#if BUILDFLAG(ENABLE_MDNS)
   if (traffic_detector_)
     traffic_detector_->Stop();
 #endif
@@ -329,6 +329,10 @@ void PrivetNotificationService::Start() {
 
 void PrivetNotificationService::OnNotificationsEnabledChanged() {
 #if BUILDFLAG(ENABLE_MDNS)
+  if (traffic_detector_)
+    traffic_detector_->Stop();
+  traffic_detector_ = nullptr;
+
   if (IsForced()) {
     StartLister();
   } else if (*enable_privet_notification_member_) {
@@ -339,7 +343,6 @@ void PrivetNotificationService::OnNotificationsEnabledChanged() {
             base::Bind(&PrivetNotificationService::StartLister, AsWeakPtr()));
     traffic_detector_->Start();
   } else {
-    traffic_detector_ = nullptr;
     device_lister_.reset();
     service_discovery_client_ = nullptr;
     privet_notifications_listener_.reset();
@@ -357,9 +360,6 @@ void PrivetNotificationService::OnNotificationsEnabledChanged() {
 
 void PrivetNotificationService::StartLister() {
   ReportPrivetUmaEvent(PRIVET_LISTER_STARTED);
-#if BUILDFLAG(ENABLE_MDNS)
-  traffic_detector_ = nullptr;
-#endif  // ENABLE_MDNS
   service_discovery_client_ =
       local_discovery::ServiceDiscoverySharedClient::GetInstance();
   device_lister_.reset(

chrome/browser/printing/cloud_print/privet_notifications.h

@@ -7,6 +7,7 @@
 
 #include <map>
 #include <memory>
+#include <set>
 #include <string>
 
 #include "chrome/browser/printing/cloud_print/privet_device_lister.h"
@@ -36,7 +37,7 @@ struct DeviceDescription;
 
 #if BUILDFLAG(ENABLE_MDNS)
 class PrivetTrafficDetector;
-#endif  // ENABLE_MDNS
+#endif
 
 // Contains logic related to notifications not tied actually displaying them.
 class PrivetNotificationsListener  {
@@ -140,7 +141,7 @@ class PrivetNotificationService
 
 #if BUILDFLAG(ENABLE_MDNS)
   scoped_refptr<PrivetTrafficDetector> traffic_detector_;
-#endif  // ENABLE_MDNS
+#endif
 };
 
 class PrivetNotificationDelegate : public message_center::NotificationDelegate {