DevTools: report adding mutation event listener as a violations.

third_party/WebKit/Source/core/frame/PerformanceMonitor.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/frame/PerformanceMonitor.h"
 
 #include "bindings/core/v8/ScheduledAction.h"
 #include "bindings/core/v8/ScriptEventListener.h"
 #include "bindings/core/v8/SourceLocation.h"
 #include "core/CoreProbeSink.h"
@@ skipping 266 matching lines @@
     Violation violation,
     const String& text,
     double time,
     std::unique_ptr<SourceLocation> location) {
   ClientThresholds* client_thresholds = subscriptions_.at(violation);
   if (!client_thresholds)
     return;
   if (!location)
     location = SourceLocation::Capture(context);
   for (const auto& it : *client_thresholds) {
-    if (it.value < time) {
-      if (!location)
-        location = SourceLocation::Capture(context);
+    if (it.value < time)
       it.key->ReportGenericViolation(violation, text, time, location.get());
-    }
   }
 }
 
 DEFINE_TRACE(PerformanceMonitor) {
   visitor->Trace(local_root_);
   visitor->Trace(task_execution_context_);
   visitor->Trace(subscriptions_);
 }
 
 }  // namespace blink