[CrOS Tether] Remove notifications when they have been tapped.

chrome/browser/chromeos/net/tether_notification_presenter.cc

Index: chrome/browser/chromeos/net/tether_notification_presenter.cc
diff --git a/chrome/browser/chromeos/net/tether_notification_presenter.cc b/chrome/browser/chromeos/net/tether_notification_presenter.cc
index 3648c3a485647991fb74811b21af06d39a274e8b..590ac5f3b47405fd996f98ec8fe8e53a22639384 100644
--- a/chrome/browser/chromeos/net/tether_notification_presenter.cc
+++ b/chrome/browser/chromeos/net/tether_notification_presenter.cc
@@ -191,6 +191,7 @@ void TetherNotificationPresenter::OnNotificationClicked(
   PA_LOG(INFO) << "Notification with ID " << notification_id << " was clicked.";
   settings_ui_delegate_->ShowSettingsSubPageForProfile(profile_,
                                                        kTetherSettingsSubpage);
+  message_center_->RemoveNotification(notification_id, true /* by_user */);
 }
 
 void TetherNotificationPresenter::OnNotificationButtonClicked(
@@ -203,6 +204,7 @@ void TetherNotificationPresenter::OnNotificationButtonClicked(
   if (notification_id == kPotentialHotspotNotificationId && button_index == 0) {
     network_connect_->ConnectToNetworkId(hotspot_nearby_device_.GetDeviceId());
   }
+  message_center_->RemoveNotification(notification_id, true /* by_user */);
 }
 
 void TetherNotificationPresenter::SetSettingsUiDelegateForTesting(