(Re-)introduce AncestorThrottle to handle 'X-Frame-Options'.

third_party/WebKit/Source/platform/network/HTTPParsers.h

Index: third_party/WebKit/Source/platform/network/HTTPParsers.h
diff --git a/third_party/WebKit/Source/platform/network/HTTPParsers.h b/third_party/WebKit/Source/platform/network/HTTPParsers.h
index a4941d8d1d6010c285d6f726ebd0e097680f2583..4eaf7f00a6cf11ccbd6d4e58db0e534a0e95193b 100644
--- a/third_party/WebKit/Source/platform/network/HTTPParsers.h
+++ b/third_party/WebKit/Source/platform/network/HTTPParsers.h
@@ -58,14 +58,6 @@ enum ContentTypeOptionsDisposition {
   ContentTypeOptionsNosniff
 };
 
-enum XFrameOptionsDisposition {
-  XFrameOptionsInvalid,
-  XFrameOptionsDeny,
-  XFrameOptionsSameOrigin,
-  XFrameOptionsAllowAll,
-  XFrameOptionsConflict
-};
-
 // Be sure to update the behavior of
 // XSSAuditor::combineXSSProtectionHeaderAndCSP whenever you change this enum's
 // content or ordering.
@@ -135,8 +127,6 @@ parseXSSProtectionHeader(const String& header,
                          String& failureReason,
                          unsigned& failurePosition,
                          String& reportURL);
-PLATFORM_EXPORT XFrameOptionsDisposition
-parseXFrameOptionsHeader(const String&);
 PLATFORM_EXPORT CacheControlHeader
 parseCacheControlDirectives(const AtomicString& cacheControlHeader,
                             const AtomicString& pragmaHeader);