Updated error message in PerformanceObserver.observe

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

 // Copyright 2015 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/timing/PerformanceObserver.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/PerformanceObserverCallback.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/timing/PerformanceBase.h"
@@ skipping 31 matching lines @@
   }
 
   PerformanceEntryTypeMask entryTypes = PerformanceEntry::Invalid;
   if (observerInit.hasEntryTypes() && observerInit.entryTypes().size()) {
     const Vector<String>& sequence = observerInit.entryTypes();
     for (const auto& entryTypeString : sequence)
       entryTypes |= PerformanceEntry::toEntryTypeEnum(entryTypeString);
   }
   if (entryTypes == PerformanceEntry::Invalid) {
     exceptionState.throwTypeError(
-        "A Performance Observer MUST have a non-empty entryTypes attribute.");
+        "A Performance Observer MUST have at least one valid entryType in its "
+        "entryTypes attribute.");
     return;
   }
   m_filterOptions = entryTypes;
   if (m_isRegistered)
     m_performance->updatePerformanceObserverFilterOptions();
   else
     m_performance->registerPerformanceObserver(*this);
   m_isRegistered = true;
 }
 
@@ skipping 34 matching lines @@
   visitor->trace(m_callback);
   visitor->trace(m_performance);
   visitor->trace(m_performanceEntries);
 }
 
 DEFINE_TRACE_WRAPPERS(PerformanceObserver) {
   visitor->traceWrappers(m_callback);
 }
 
 }  // namespace blink