Update HTTPHeaderMap wrappers to use AtomicString type for header values

Source/core/inspector/InspectorResourceAgent.cpp

Index: Source/core/inspector/InspectorResourceAgent.cpp
diff --git a/Source/core/inspector/InspectorResourceAgent.cpp b/Source/core/inspector/InspectorResourceAgent.cpp
index 84eef9ecf30f6c0451284376ff5b4c7f67a39bad..3e61593c76d6729cb60ba74c0d61c8c43230766b 100644
--- a/Source/core/inspector/InspectorResourceAgent.cpp
+++ b/Source/core/inspector/InspectorResourceAgent.cpp
@@ -439,7 +439,7 @@ void InspectorResourceAgent::documentThreadableLoaderStartedLoadingForClient(uns
     m_resourcesData->setXHRReplayData(requestId, xhrReplayData);
 }
 
-void InspectorResourceAgent::willLoadXHR(XMLHttpRequest*, ThreadableLoaderClient* client, const String& method, const KURL& url, bool async, PassRefPtr<FormData> formData, const HTTPHeaderMap& headers, bool includeCredentials)
+void InspectorResourceAgent::willLoadXHR(XMLHttpRequest*, ThreadableLoaderClient* client, const AtomicString& method, const KURL& url, bool async, PassRefPtr<FormData> formData, const HTTPHeaderMap& headers, bool includeCredentials)
 {
     RefPtr<XHRReplayData> xhrReplayData = XHRReplayData::create(method, urlWithoutFragment(url), async, formData, includeCredentials);
     HTTPHeaderMap::const_iterator end = headers.end();