Drop GetFrame()->GetDocument() usage in FrameFetchContext

third_party/WebKit/Source/core/loader/BaseFetchContext.cpp

 // Copyright 2017 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 "core/loader/BaseFetchContext.h"
 
 #include "core/dom/ExecutionContext.h"
 #include "core/frame/ContentSettingsClient.h"
 #include "core/frame/Settings.h"
 #include "core/inspector/ConsoleMessage.h"
@@ skipping 239 matching lines @@
 
   // SVG Images have unique security rules that prevent all subresource requests
   // except for data urls.
   if (type != Resource::kMainResource && IsSVGImageChromeClient() &&
       !url.ProtocolIsData())
     return ResourceRequestBlockedReason::kOrigin;
 
   // Measure the number of legacy URL schemes ('ftp://') and the number of
   // embedded-credential ('http://user:password@...') resources embedded as
   // subresources.
-  if (resource_request.GetFrameType() != WebURLRequest::kFrameTypeTopLevel) {
-    if (GetMainResourceSecurityContext() &&
-        SchemeRegistry::ShouldTreatURLSchemeAsLegacy(url.Protocol()) &&
+  WebURLRequest::FrameType frame_type = resource_request.GetFrameType();
+  if (frame_type != WebURLRequest::kFrameTypeTopLevel) {
+    bool is_subresource = frame_type == WebURLRequest::kFrameTypeNone;
+    SecurityContext* embedding_context =
+        is_subresource ? &execution_context_->GetSecurityContext()
+                       : GetParentSecurityContext();

[Nate Chapin, 2017/04/28 21:33:31]

The only reason GetMainResourceSecurityContext() needed to reference
GetFrame()->GetDocument() was to handle the iframe load case. In that case,
there must be a parent with a valid SecurityContext (whether local or remote),
and technically the parent is what's embedding things we want to deprecate
anyway. Reference this frame's for subresources, and the parent's for iframe
main resources.

[kinuko, 2017/04/29 14:10:20]

This is much clearer now, thanks!

+    DCHECK(embedding_context);
+    if (SchemeRegistry::ShouldTreatURLSchemeAsLegacy(url.Protocol()) &&
         !SchemeRegistry::ShouldTreatURLSchemeAsLegacy(
-            GetMainResourceSecurityContext()
-                ->GetSecurityOrigin()
-                ->Protocol())) {
+            embedding_context->GetSecurityOrigin()->Protocol())) {
       CountDeprecation(UseCounter::kLegacyProtocolEmbeddedAsSubresource);
 
       // TODO(mkwst): Enabled by default in M59. Drop the runtime-enabled check
       // in M60: https://www.chromestatus.com/feature/5709390967472128
       if (RuntimeEnabledFeatures::blockLegacySubresourcesEnabled())
         return ResourceRequestBlockedReason::kOrigin;
     }
 
     if ((!url.User().IsEmpty() || !url.Pass().IsEmpty()) &&
         resource_request.GetRequestContext() !=
@@ skipping 36 matching lines @@
 
   return ResourceRequestBlockedReason::kNone;
 }
 
 DEFINE_TRACE(BaseFetchContext) {
   visitor->Trace(execution_context_);
   FetchContext::Trace(visitor);
 }
 
 }  // namespace blink