Add an assert that TracedValue builder closes only most recently opened container

Source/platform/TracedValue.h

 // Copyright 2014 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.
 
 #ifndef TracedValue_h
 #define TracedValue_h
 
 #include "platform/EventTracer.h"
 
 #include "wtf/PassRefPtr.h"
@@ skipping 32 matching lines @@
 
     Vector<RefPtr<JSONValue> > m_stack;
 };
 
 template <class OwnerType>
 class TracedDictionary : public TracedValueBase {
     WTF_MAKE_NONCOPYABLE(TracedDictionary);
 public:
     OwnerType& endDictionary()
     {
+        ASSERT(m_stack.size() == nestingLevel);
         endCurrentDictionary();
         return *reinterpret_cast<OwnerType*>(this);
     }
 
     TracedDictionary<TracedDictionary<OwnerType> >& beginDictionary(const char* name)
     {
         beginDictionaryNamed(name);
         return *reinterpret_cast<TracedDictionary<TracedDictionary<OwnerType> >* >(this);
     }
     TracedArray<TracedDictionary<OwnerType> >& beginArray(const char* name)
@@ skipping 15 matching lines @@
     {
         TracedValueBase::setBoolean(name, value);
         return *this;
     }
     TracedDictionary<OwnerType>& setString(const char* name, const String& value)
     {
         TracedValueBase::setString(name, value);
         return *this;
     }
 
+    static const size_t nestingLevel = OwnerType::nestingLevel + 1;
+
 private:
     TracedDictionary();
     ~TracedDictionary();
 };
 
 template <class OwnerType>
 class TracedArray : public TracedValueBase {
     WTF_MAKE_NONCOPYABLE(TracedArray);
 public:
     TracedDictionary<TracedArray<OwnerType> >& beginDictionary()
     {
         pushDictionary();
         return *reinterpret_cast<TracedDictionary<TracedArray<OwnerType> >* >(this);
     }
     TracedDictionary<TracedArray<OwnerType> >& beginArray()
     {
         pushArray();
         return *reinterpret_cast<TracedDictionary<TracedArray<OwnerType> >* >(this);
     }
     OwnerType& endArray()
     {
+        ASSERT(m_stack.size() == nestingLevel);
         endCurrentArray();
         return *reinterpret_cast<OwnerType*>(this);
     }
 
     TracedArray<OwnerType>& pushInteger(int value)
     {
         TracedValueBase::pushInteger(value);
         return *this;
     }
     TracedArray<OwnerType>& pushDouble(double value)
     {
         TracedValueBase::pushDouble(value);
         return *this;
     }
     TracedArray<OwnerType>& pushBoolean(bool value)
     {
         TracedValueBase::pushBoolean(value);
         return *this;
     }
     TracedArray<OwnerType>& pushString(const String& value)
     {
         TracedValueBase::pushString(value);
         return *this;
     }
 
+    static const size_t nestingLevel = OwnerType::nestingLevel + 1;
+
 private:
     TracedArray();
     ~TracedArray();
 };
 
 class PLATFORM_EXPORT TracedValue : public TracedValueBase {
     WTF_MAKE_NONCOPYABLE(TracedValue);
 public:
     TracedValue();
     ~TracedValue();
@@ skipping 14 matching lines @@
     {
         TracedValueBase::setBoolean(name, value);
         return *this;
     }
     TracedValue& setString(const char* name, const String& value)
     {
         TracedValueBase::setString(name, value);
         return *this;
     }
     PassRefPtr<TraceEvent::ConvertableToTraceFormat> finish();
+
+    static const size_t nestingLevel = 1;
 };
 
 } // namespace WebCore
 
 #endif // TracedValue_h