Add link preload as=document support

content/child/web_url_request_util.cc

 // 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 "content/child/web_url_request_util.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <limits>
@@ skipping 61 matching lines @@
     DCHECK(requestContext == WebURLRequest::RequestContextForm ||
            requestContext == WebURLRequest::RequestContextFrame ||
            requestContext == WebURLRequest::RequestContextHyperlink ||
            requestContext == WebURLRequest::RequestContextIframe ||
            requestContext == WebURLRequest::RequestContextInternal ||
            requestContext == WebURLRequest::RequestContextLocation);
     if (request.getFrameType() == WebURLRequest::FrameTypeTopLevel ||
         request.getFrameType() == WebURLRequest::FrameTypeAuxiliary) {
       return RESOURCE_TYPE_MAIN_FRAME;
     }
-    if (request.getFrameType() == WebURLRequest::FrameTypeNested)
+    if (request.getFrameType() == WebURLRequest::FrameTypeNested ||
+        request.getFrameType() == WebURLRequest::FrameTypePreload) {
       return RESOURCE_TYPE_SUB_FRAME;
+    }
     NOTREACHED();
     return RESOURCE_TYPE_SUB_RESOURCE;
   }
 
   switch (requestContext) {
     // CSP report
     case WebURLRequest::RequestContextCSPReport:
       return RESOURCE_TYPE_CSP_REPORT;
 
     // Favicon
@@ skipping 399 matching lines @@
                                      bool stale_copy_in_cache,
                                      int reason,
                                      bool was_ignored_by_handler) {
   blink::WebURLError error =
       CreateWebURLError(unreachable_url, stale_copy_in_cache, reason);
   error.wasIgnoredByHandler = was_ignored_by_handler;
   return error;
 }
 
 }  // namespace content