Do not show image placeholders for CSS sprites

third_party/WebKit/Source/core/css/CSSImageSetValue.cpp

 /*
  * Copyright (C) 2012 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 12 matching lines @@
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/css/CSSImageSetValue.h"
 
 #include <algorithm>
 #include "core/css/CSSImageValue.h"
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/dom/Document.h"
 #include "core/frame/LocalFrame.h"
+#include "core/frame/Settings.h"
 #include "core/loader/resource/ImageResourceContent.h"
 #include "core/style/StyleFetchedImageSet.h"
 #include "core/style/StyleInvalidImage.h"
 #include "platform/loader/fetch/FetchInitiatorTypeNames.h"
 #include "platform/loader/fetch/FetchParameters.h"
 #include "platform/loader/fetch/ResourceFetcher.h"
 #include "platform/loader/fetch/ResourceLoaderOptions.h"
 #include "platform/weborigin/KURL.h"
 #include "platform/weborigin/SecurityPolicy.h"
 #include "platform/wtf/text/StringBuilder.h"
@@ skipping 51 matching lines @@
 }
 
 StyleImage* CSSImageSetValue::CachedImage(float device_scale_factor) const {
   DCHECK(!IsCachePending(device_scale_factor));
   return cached_image_.Get();
 }
 
 StyleImage* CSSImageSetValue::CacheImage(
     const Document& document,
     float device_scale_factor,
+    FetchParameters::PlaceholderImageRequestType placeholder_image_request_type,
     CrossOriginAttributeValue cross_origin) {
   if (!images_in_set_.size())
     FillImageSet();
 
   if (IsCachePending(device_scale_factor)) {
     // FIXME: In the future, we want to take much more than deviceScaleFactor
     // into acount here. All forms of scale should be included:
     // Page::PageScaleFactor(), LocalFrame::PageZoomFactor(), and any CSS
     // transforms. https://bugs.webkit.org/show_bug.cgi?id=81698
     ImageWithScale image = BestImageForScaleFactor(device_scale_factor);
     ResourceRequest resource_request(document.CompleteURL(image.image_url));
     resource_request.SetHTTPReferrer(image.referrer);
     ResourceLoaderOptions options(kAllowStoredCredentials,
                                   kClientRequestedCredentials);
     options.initiator_info.name = FetchInitiatorTypeNames::css;
     FetchParameters params(resource_request, options);
 
     if (cross_origin != kCrossOriginAttributeNotSet) {
       params.SetCrossOriginAccessControl(document.GetSecurityOrigin(),
                                          cross_origin);
     }
-    if (document.GetFrame())
+    if (document.GetFrame() && document.GetSettings() &&
+        document.GetSettings()->GetFetchImagePlaceholders() &&

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

Could you remove the Settings checks here? That logic (plus logic to allow
placeholders when Client LoFi is on) is handled by
document.GetFrame()->MaybeAllowImagePlaceholder(params).

[rajendrant, 2017/06/21 19:00:57]

Done.

+        placeholder_image_request_type == FetchParameters::kAllowPlaceholder)
       document.GetFrame()->MaybeAllowImagePlaceholder(params);
 
     if (ImageResourceContent* cached_image =
             ImageResourceContent::Fetch(params, document.Fetcher())) {
       cached_image_ = StyleFetchedImageSet::Create(
           cached_image, image.scale_factor, this, params.Url());
     } else {
       cached_image_ = StyleInvalidImage::Create(image.image_url);
     }
     cached_scale_factor_ = device_scale_factor;
@@ skipping 48 matching lines @@
 CSSImageSetValue* CSSImageSetValue::ValueWithURLsMadeAbsolute() {
   CSSImageSetValue* value = CSSImageSetValue::Create();
   for (auto& item : *this)
     item->IsImageValue()
         ? value->Append(*ToCSSImageValue(*item).ValueWithURLMadeAbsolute())
         : value->Append(*item);
   return value;
 }
 
 }  // namespace blink