[Not for review] Add traces for crbug.com/726626

third_party/WebKit/Source/core/timing/PerformanceBase.cpp

Index: third_party/WebKit/Source/core/timing/PerformanceBase.cpp
diff --git a/third_party/WebKit/Source/core/timing/PerformanceBase.cpp b/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
index 07d48eecd5039101c9573b01bcdb05dba6bbd426..bcf0ceb9f2293ba3b609cade3f7bd9354292e837 100644
--- a/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
+++ b/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
@@ -45,6 +45,7 @@
 #include "core/timing/PerformanceServerTiming.h"
 #include "core/timing/PerformanceUserTiming.h"
 #include "platform/RuntimeEnabledFeatures.h"
+#include "platform/instrumentation/tracing/TraceEvent.h"
 #include "platform/loader/fetch/ResourceResponse.h"
 #include "platform/loader/fetch/ResourceTimingInfo.h"
 #include "platform/weborigin/SecurityOrigin.h"
@@ -604,6 +605,7 @@ DOMHighResTimeStamp PerformanceBase::MonotonicTimeToDOMHighResTimeStamp(
 }
 
 DOMHighResTimeStamp PerformanceBase::now() const {
+  TRACE_EVENT0("ServiceWorker", "PerformanceBase::now");
   return MonotonicTimeToDOMHighResTimeStamp(MonotonicallyIncreasingTime());
 }