Fix flaky tests by disabling DeviceDiscoveryNotification service.

chrome/browser/ui/webui/local_discovery/local_discovery_ui_browsertest.cc

Index: chrome/browser/ui/webui/local_discovery/local_discovery_ui_browsertest.cc
diff --git a/chrome/browser/ui/webui/local_discovery/local_discovery_ui_browsertest.cc b/chrome/browser/ui/webui/local_discovery/local_discovery_ui_browsertest.cc
index 2081f933c77b257340922f4d31b1b40898bf5392..9971504107a809908f0af406e3ac1074a05be67d 100644
--- a/chrome/browser/ui/webui/local_discovery/local_discovery_ui_browsertest.cc
+++ b/chrome/browser/ui/webui/local_discovery/local_discovery_ui_browsertest.cc
@@ -447,6 +447,7 @@ class LocalDiscoveryUITest : public WebUIBrowserTest {
     command_line->AppendSwitchASCII(chromeos::switches::kLoginProfile,
                                     chrome::kTestUserProfileDir);
 #endif
+    command_line->AppendSwitch(switches::kDisableDeviceDiscoveryNotifications);
     WebUIBrowserTest::SetUpCommandLine(command_line);
   }
 
@@ -516,7 +517,7 @@ IN_PROC_BROWSER_TEST_F(LocalDiscoveryUITest, AddRowTest) {
 }
 
 // Flaky: http://crbug.com/660669.
-IN_PROC_BROWSER_TEST_F(LocalDiscoveryUITest, DISABLED_RegisterTest) {
+IN_PROC_BROWSER_TEST_F(LocalDiscoveryUITest, RegisterTest) {
   TestMessageLoopCondition condition_token_claimed;
 
   ui_test_utils::NavigateToURL(browser(), GURL(