Link prefetch fetches deferred until onload

third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp

Index: third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp
diff --git a/third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp b/third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp
index a5eae6c5bf861db7dc1fd4028a4489e01506f60b..5a63a7bf656ef5b2c78f5c7b7c9475d2b9b78615 100644
--- a/third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp
+++ b/third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp
@@ -262,7 +262,8 @@ ResourceFetcher::ResourceFetcher(FetchContext* newContext)
       m_autoLoadImages(true),
       m_imagesEnabled(true),
       m_allowStaleResources(false),
-      m_imageFetched(false) {}
+      m_imageFetched(false),
+      m_onloadDeferredResourcesLoaded(false) {}
 
 ResourceFetcher::~ResourceFetcher() {}
 
@@ -285,6 +286,13 @@ bool ResourceFetcher::resourceNeedsLoad(Resource* resource,
     return false;
   if (resource->isImage() && shouldDeferImageLoad(resource->url()))
     return false;
+  if (resource->getType() == Resource::LinkPrefetch &&
+      !m_onloadDeferredResourcesLoaded) {
+    if (!m_onloadDeferredResources)
+      m_onloadDeferredResources = new HeapVector<Member<Resource>>;
+    m_onloadDeferredResources->push_back(resource);
+    return false;
+  }
   return policy != Use || resource->stillNeedsLoad();
 }
 
@@ -1049,6 +1057,17 @@ void ResourceFetcher::reloadImagesIfNotDeferred() {
   }
 }
 
+void ResourceFetcher::loadOnloadDeferredResources() {
+  if (!m_onloadDeferredResources)
+    return;
+  for (auto& resource : *m_onloadDeferredResources) {
+    if (resource->stillNeedsLoad())
+      startLoad(resource);
+  }
+  m_onloadDeferredResources->clear();
+  m_onloadDeferredResourcesLoaded = true;
+}
+
 void ResourceFetcher::clearContext() {
   clearPreloads(ResourceFetcher::ClearAllPreloads);
   m_context.clear();
@@ -1549,6 +1568,7 @@ DEFINE_TRACE(ResourceFetcher) {
   visitor->trace(m_nonBlockingLoaders);
   visitor->trace(m_documentResources);
   visitor->trace(m_preloads);
+  visitor->trace(m_onloadDeferredResources);
   visitor->trace(m_resourceTimingInfoMap);
 }