Add <link rel=preload> onload support for scripts and styles

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

Index: third_party/WebKit/Source/core/loader/LinkLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/LinkLoader.cpp b/third_party/WebKit/Source/core/loader/LinkLoader.cpp
index 7db397a9e10fbb0e983f1319cb5d23ea401af82e..4a35e9a473e2d575ac5ebd0aeab4f59302863d05 100644
--- a/third_party/WebKit/Source/core/loader/LinkLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/LinkLoader.cpp
@@ -90,15 +90,19 @@ void LinkLoader::linkLoadingErrorTimerFired(Timer<LinkLoader>* timer)
     m_client->linkLoadingErrored();
 }
 
-void LinkLoader::notifyFinished(Resource* resource)
+void LinkLoader::triggerEvents(Resource* resource)
 {
-    ASSERT(this->resource() == resource);
-
     if (resource->errorOccurred())
         m_linkLoadingErrorTimer.startOneShot(0, BLINK_FROM_HERE);
     else
         m_linkLoadTimer.startOneShot(0, BLINK_FROM_HERE);
+}
+
+void LinkLoader::notifyFinished(Resource* resource)
+{
+    ASSERT(this->resource() == resource);
 
+    triggerEvents(resource);
     clearResource();
 }
 
@@ -184,31 +188,59 @@ Resource::Type LinkLoader::getTypeFromAsAttribute(const String& as, Document* do
     return Resource::LinkSubresource;
 }
 
-static void preloadIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document, const String& as)
+static void createLinkPreloadResourceClient(ResourcePtr<Resource> resource, LinkLoader* linkLoader, Resource::Type type)

[Nate Chapin, 2016/01/15 18:53:58]

This could either return the LinkPreloadResourceClient or be a LinkLoader
member, so that setPreloadResourceClient doesn't need to be public.

[Yoav Weiss, 2016/01/15 21:40:25]

yeah, adding both this and preloadIfNeeded as statics on LinkLoader, to avoid
publics

 {
-    if (!document.loader())
+    if (!linkLoader || !resource)
         return;
+    OwnPtr<LinkPreloadResourceClient> resourceClient = nullptr;
+    switch (type) {
+    case Resource::Image:
+        break;
+    case Resource::Script:
+        resourceClient = LinkPreloadScriptResourceClient::create(linkLoader, resource.get());
+        break;
+    case Resource::CSSStyleSheet:
+        resourceClient = LinkPreloadStyleResourceClient::create(linkLoader, resource.get());
+        break;
+    // TODO(yoav): add support for everything below.
+    case Resource::Font:
+        break;
+    case Resource::Media:
+        break;
+    case Resource::TextTrack:
+        break;
+    case Resource::LinkSubresource:
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
 
-    if (relAttribute.isLinkPreload()) {
-        UseCounter::count(document, UseCounter::LinkRelPreload);
-        ASSERT(RuntimeEnabledFeatures::linkPreloadEnabled());
-        if (!href.isValid() || href.isEmpty()) {
-            document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, WarningMessageLevel, String("<link rel=preload> has an invalid `href` value")));
-            return;
-        }
-        Resource::Type type = LinkLoader::getTypeFromAsAttribute(as, &document);
-        ResourceRequest resourceRequest(document.completeURL(href));
-        ResourceFetcher::determineRequestContext(resourceRequest, type, false);
-        FetchRequest linkRequest(resourceRequest, FetchInitiatorTypeNames::link);
+    linkLoader->setPreloadResourceClient(resourceClient.release());
+}
 
-        linkRequest.setPriority(document.fetcher()->loadPriority(type, linkRequest));
-        Settings* settings = document.settings();
-        if (settings && settings->logPreload())
-            document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("Preload triggered for " + href.host() + href.path())));
-        linkRequest.setForPreload(true);
-        linkRequest.setAvoidBlockingOnLoad(true);
-        document.loader()->startPreload(type, linkRequest);
+static void preloadIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document, const String& as, LinkLoader* linkLoader)
+{
+    if (!document.loader() || !relAttribute.isLinkPreload())
+        return;
+
+    UseCounter::count(document, UseCounter::LinkRelPreload);
+    ASSERT(RuntimeEnabledFeatures::linkPreloadEnabled());
+    if (!href.isValid() || href.isEmpty()) {
+        document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, WarningMessageLevel, String("<link rel=preload> has an invalid `href` value")));
+        return;
     }
+    Resource::Type type = LinkLoader::getTypeFromAsAttribute(as, &document);
+    ResourceRequest resourceRequest(document.completeURL(href));
+    ResourceFetcher::determineRequestContext(resourceRequest, type, false);
+    FetchRequest linkRequest(resourceRequest, FetchInitiatorTypeNames::link);
+
+    linkRequest.setPriority(document.fetcher()->loadPriority(type, linkRequest));
+    Settings* settings = document.settings();
+    if (settings && settings->logPreload())
+        document.addConsoleMessage(ConsoleMessage::create(OtherMessageSource, DebugMessageLevel, String("Preload triggered for " + href.host() + href.path())));
+    linkRequest.setForPreload(true);
+    linkRequest.setAvoidBlockingOnLoad(true);
+    createLinkPreloadResourceClient(document.loader()->startPreload(type, linkRequest, linkLoader), linkLoader, type);

[Nate Chapin, 2016/01/15 18:53:58]

Maybe do this after preloadIfNeeded is called in loadLink()?

[Yoav Weiss, 2016/01/15 21:40:25]

not sure what you mean by that. Can you elaborate?

[Nate Chapin, 2016/01/15 21:52:44]

createLinkPreloadResourceClient() only does work if linkLoader is non-null,
which is only true when preloadIfNeeded() is called from loadLink(). Calling
createLinkPreloadResourceClient() from loadLink() means we don't need to null
check. It also means preloadIfNeeded() doesn't need a LinkLoader* parameter. 

 }
 
 bool LinkLoader::loadLinkFromHeader(const String& headerValue, Document* document, const NetworkHintsInterface& networkHintsInterface, CanLoadResources canLoadResources)
@@ -230,7 +262,7 @@ bool LinkLoader::loadLinkFromHeader(const String& headerValue, Document* documen
                 preconnectIfNeeded(relAttribute, url, *document, header.crossOrigin(), networkHintsInterface, LinkCalledFromHeader);
         } else {
             if (RuntimeEnabledFeatures::linkPreloadEnabled())
-                preloadIfNeeded(relAttribute, url, *document, header.as());
+                preloadIfNeeded(relAttribute, url, *document, header.as(), nullptr);
         }
         // TODO(yoav): Add more supported headers as needed.
     }
@@ -248,7 +280,7 @@ bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, CrossOriginAttri
     preconnectIfNeeded(relAttribute, href, document, crossOrigin, networkHintsInterface, LinkCalledFromMarkup);
 
     if (m_client->shouldLoadLink())
-        preloadIfNeeded(relAttribute, href, document, as);
+        preloadIfNeeded(relAttribute, href, document, as, this);
 
     // FIXME(crbug.com/323096): Should take care of import.
     if ((relAttribute.isLinkPrefetch() || relAttribute.isLinkSubresource()) && href.isValid() && document.frame()) {
@@ -296,6 +328,7 @@ void LinkLoader::released()
 DEFINE_TRACE(LinkLoader)
 {
     visitor->trace(m_prerender);
+    visitor->trace(m_linkPreloadResourceClient);
 }
 
 }