Use AtomicString type more consistently for mimeType / encoding

Source/platform/mhtml/ArchiveResource.cpp

Index: Source/platform/mhtml/ArchiveResource.cpp
diff --git a/Source/platform/mhtml/ArchiveResource.cpp b/Source/platform/mhtml/ArchiveResource.cpp
index ccd97ade36d062a7067cd2ca5bfd5380cdd3bb42..6b00e813051460c3c41fd710ec7477842de22f5e 100644
--- a/Source/platform/mhtml/ArchiveResource.cpp
+++ b/Source/platform/mhtml/ArchiveResource.cpp
@@ -33,7 +33,7 @@
 
 namespace WebCore {
 
-inline ArchiveResource::ArchiveResource(PassRefPtr<SharedBuffer> data, const KURL& url, const String& mimeType, const String& textEncoding, const String& frameName, const ResourceResponse& response)
+inline ArchiveResource::ArchiveResource(PassRefPtr<SharedBuffer> data, const KURL& url, const AtomicString& mimeType, const AtomicString& textEncoding, const String& frameName, const ResourceResponse& response)
     : m_url(url)
     , m_response(response)
     , m_data(data)
@@ -44,7 +44,7 @@ inline ArchiveResource::ArchiveResource(PassRefPtr<SharedBuffer> data, const KUR
     ASSERT(m_data);
 }
 
-PassRefPtr<ArchiveResource> ArchiveResource::create(PassRefPtr<SharedBuffer> data, const KURL& url, const String& mimeType, const String& textEncoding, const String& frameName, const ResourceResponse& response)
+PassRefPtr<ArchiveResource> ArchiveResource::create(PassRefPtr<SharedBuffer> data, const KURL& url, const AtomicString& mimeType, const AtomicString& textEncoding, const String& frameName, const ResourceResponse& response)
 {
     if (!data)
         return 0;