Refactoring: Extract DocumentInit for capture Document construction parameter.

Source/core/html/MediaDocument.cpp

Index: Source/core/html/MediaDocument.cpp
diff --git a/Source/core/html/MediaDocument.cpp b/Source/core/html/MediaDocument.cpp
index c3a5511e02b0e11faae1565722cebe9dc7efcbf6..178ea6359d4506783d19b9a12cbe82b6aabe6904 100644
--- a/Source/core/html/MediaDocument.cpp
+++ b/Source/core/html/MediaDocument.cpp
@@ -117,8 +117,8 @@ size_t MediaDocumentParser::appendBytes(const char*, size_t)
     return 0;
 }
     
-MediaDocument::MediaDocument(Frame* frame, const KURL& url)
-    : HTMLDocument(frame, url, MediaDocumentClass)
+MediaDocument::MediaDocument(const DocumentInitializer& initializer)
+    : HTMLDocument(initializer, MediaDocumentClass)
 {
     setCompatibilityMode(QuirksMode);
     lockCompatibilityMode();