Add OriginTrial flag for Long Task Observer

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

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 18 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/timing/Performance.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
 #include "core/inspector/InspectedFrames.h"
 #include "core/inspector/InspectorWebPerfAgent.h"
 #include "core/loader/DocumentLoader.h"
+#include "core/origin_trials/OriginTrials.h"
 #include "core/timing/PerformanceTiming.h"
 
 namespace blink {
 
 static double toTimeOrigin(LocalFrame* frame) {
   if (!frame)
     return 0.0;
 
   Document* document = frame->document();
   if (!document)
@@ skipping 30 matching lines @@
 
 PerformanceTiming* Performance::timing() const {
   if (!m_timing)
     m_timing = PerformanceTiming::create(frame());
 
   return m_timing.get();
 }
 
 void Performance::updateLongTaskInstrumentation() {
   if (hasObserverFor(PerformanceEntry::LongTask) && !m_longTaskInspectorAgent) {
+    if (!frame() || !frame()->document() ||
+        !OriginTrials::longTaskObserverEnabled(frame()->document()))
+      return;
     m_longTaskInspectorAgent = new InspectorWebPerfAgent(frame());
     m_longTaskInspectorAgent->enable();
   } else if (!hasObserverFor(PerformanceEntry::LongTask) &&
              m_longTaskInspectorAgent) {
     m_longTaskInspectorAgent->disable();
     m_longTaskInspectorAgent = nullptr;
   }
 }
 
 DEFINE_TRACE(Performance) {
   visitor->trace(m_navigation);
   visitor->trace(m_timing);
   visitor->trace(m_longTaskInspectorAgent);
   DOMWindowProperty::trace(visitor);
   PerformanceBase::trace(visitor);
 }
 
 }  // namespace blink