Do not show image placeholders for CSS sprites

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

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 173 matching lines @@
 
 const KURL& DocumentLoader::Url() const {
   return request_.Url();
 }
 
 Resource* DocumentLoader::StartPreload(Resource::Type type,
                                        FetchParameters& params) {
   Resource* resource = nullptr;
   switch (type) {
     case Resource::kImage:
-      if (frame_)
+      if (frame_ && frame_->GetSettings() &&
+          frame_->GetSettings()->GetFetchImagePlaceholders()) {

[sclittle, 2017/06/13 00:28:27]

Could you remove the Settings checks here? They're already handled by
frame_->MaybeAllowImagePlaceholder.

[rajendrant, 2017/06/21 19:00:58]

Done.

         frame_->MaybeAllowImagePlaceholder(params);
+      }
       resource = ImageResource::Fetch(params, Fetcher());
       break;
     case Resource::kScript:
       resource = ScriptResource::Fetch(params, Fetcher());
       break;
     case Resource::kCSSStyleSheet:
       resource = CSSStyleSheetResource::Fetch(params, Fetcher());
       break;
     case Resource::kFont:
       resource = FontResource::Fetch(params, Fetcher());
@@ skipping 885 matching lines @@
                      InstallNewDocumentReason::kJavascriptURL,
                      kForceSynchronousParsing, KURL());
   if (!source.IsNull())
     writer_->AppendReplacingData(source);
   EndWriting();
 }
 
 DEFINE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 }  // namespace blink