Mark WorkerTest.QueuedSharedWorkerStartedFromOtherTab as flaky on Mac.

chrome/worker/worker_uitest.cc

Index: chrome/worker/worker_uitest.cc
diff --git a/chrome/worker/worker_uitest.cc b/chrome/worker/worker_uitest.cc
index 38b2351e0d6dd4cb1fcc5a9a568477bc3e48df44..09e6c39935e47927e63cf3801e8ef5ac56e1da06 100644
--- a/chrome/worker/worker_uitest.cc
+++ b/chrome/worker/worker_uitest.cc
@@ -637,7 +637,15 @@ TEST_F(WorkerTest, FLAKY_MultipleTabsQueuedSharedWorker) {
   ASSERT_TRUE(WaitForProcessCountToBe(3, max_workers_per_tab));
 }
 
-TEST_F(WorkerTest, QueuedSharedWorkerStartedFromOtherTab) {
+// Only flaky on Mac  http://crbug.com/48148
+#if defined(OS_MACOSX)
+#define MAYBE_QueuedSharedWorkerStartedFromOtherTab \
+    FLAKY_QueuedSharedWorkerStartedFromOtherTab
+#else
+#define MAYBE_QueuedSharedWorkerStartedFromOtherTab \
+    QueuedSharedWorkerStartedFromOtherTab
+#endif
+TEST_F(WorkerTest, MAYBE_QueuedSharedWorkerStartedFromOtherTab) {
   // Tests to make sure that queued shared workers are started up when
   // an instance is launched from another tab.
   int max_workers_per_tab = WorkerService::kMaxWorkersPerTabWhenSeparate;