Avoid sending mixed-content requests for ImageSet contexts

third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.cpp

Index: third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.cpp
diff --git a/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.cpp b/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.cpp
index 912402fb8c636c037575af2d936670ccded96c7e..e533a3ab78fb0f51c98e268c844c994998fb218e 100644
--- a/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.cpp
+++ b/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.cpp
@@ -241,7 +241,8 @@ void CSSPreloadScanner::EmitRule(const SegmentedString& source) {
     auto request = PreloadRequest::CreateIfNeeded(
         FetchInitiatorTypeNames::css, position, url,
         *predicted_base_element_url_, Resource::kCSSStyleSheet,
-        referrer_policy_, PreloadRequest::kBaseUrlIsReferrer);
+        referrer_policy_, PreloadRequest::kBaseUrlIsReferrer,
+        ResourceFetcher::kImageNotImageSet);
     if (request) {
       // FIXME: Should this be including the charset in the preload request?
       requests_->push_back(std::move(request));