Timeline: return 'null' from JSCallStack::asTraceFormat() when stack is absent

Source/core/inspector/InspectorTraceEvents.cpp

 // 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.
 
 #include "config.h"
 #include "core/inspector/InspectorTraceEvents.h"
 
 #include "bindings/v8/ScriptCallStackFactory.h"
 #include "bindings/v8/ScriptGCEvent.h"
 #include "bindings/v8/ScriptSourceCode.h"
@@ skipping 18 matching lines @@
 namespace WebCore {
 
 namespace {
 
 class JSCallStack : public TraceEvent::ConvertableToTraceFormat  {
 public:
     explicit JSCallStack(PassRefPtr<ScriptCallStack> callstack) : m_callstack(callstack) { }
     virtual String asTraceFormat() const
     {
         if (!m_callstack)
-            return "[]";
+            return "null";
         return m_callstack->buildInspectorArray()->toJSONString();
     }
 
 private:
     RefPtr<ScriptCallStack> m_callstack;
 };
 
 String toHexString(void* p)
 {
     return String::format("0x%" PRIx64, static_cast<uint64>(reinterpret_cast<intptr_t>(p)));
@@ skipping 275 matching lines @@
     data->setNumber("jsHeapSizeUsed", static_cast<double>(usedHeapSize()));
     return TracedValue::fromJSONValue(data);
 }
 
 PassRefPtr<TraceEvent::ConvertableToTraceFormat> InspectorCallStackEvent::currentCallStack()
 {
     return adoptRef(new JSCallStack(createScriptCallStack(ScriptCallStack::maxCallStackSizeToCapture, true)));
 }
 
 }