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

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

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 53 matching lines @@
         UseCounter::count(document, UseCounter::LinkRelNext);
     }
 
     return result;
 }
 
 LinkLoader::LinkLoader(LinkLoaderClient* client)
     : m_client(client)
     , m_linkLoadTimer(this, &LinkLoader::linkLoadTimerFired)
     , m_linkLoadingErrorTimer(this, &LinkLoader::linkLoadingErrorTimerFired)
+    , m_weakPtrFactory(this)
 {
 }
 
 LinkLoader::~LinkLoader()
 {
 }
 
 void LinkLoader::linkLoadTimerFired(Timer<LinkLoader>* timer)
 {
     ASSERT_UNUSED(timer, timer == &m_linkLoadTimer);
     m_client->linkLoaded();
 }
 
 void LinkLoader::linkLoadingErrorTimerFired(Timer<LinkLoader>* timer)
 {
     ASSERT_UNUSED(timer, timer == &m_linkLoadingErrorTimer);
     m_client->linkLoadingErrored();
 }
 
+void LinkLoader::triggerEvents(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);
 
-    if (resource->errorOccurred())
-        m_linkLoadingErrorTimer.startOneShot(0, BLINK_FROM_HERE);
-    else
-        m_linkLoadTimer.startOneShot(0, BLINK_FROM_HERE);
-
+    triggerEvents(resource);
     clearResource();
 }
 
 void LinkLoader::didStartPrerender()
 {
     m_client->didStartLinkPrerender();
 }
 
 void LinkLoader::didStopPrerender()
 {
@@ skipping 65 matching lines @@
     if (equalIgnoringCase(as, "font"))
         return Resource::Font;
     if (equalIgnoringCase(as, "track"))
         return Resource::TextTrack;
     if (document && !as.isEmpty())
         document->addConsoleMessage(ConsoleMessage::create(OtherMessageSource, WarningMessageLevel, String("<link rel=preload> must have a valid `as` value")));
     // TODO(yoav): Is this correct? If as is missing or invalid, it should be subject to "connect-src" CSP directives.
     return Resource::LinkSubresource;
 }
 
-static void preloadIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document, const String& as)
+static void preloadIfNeeded(const LinkRelAttribute& relAttribute, const KURL& href, Document& document, const String& as, LinkLoader* linkLoader)

[Nate Chapin, 2016/01/13 23:52:23]

Should this be a private member of LinkLoader if we're going to start accessing
LinkLoader properties?

[Yoav Weiss, 2016/01/14 10:10:02]

This has to remain static since it's called from loadLinkFromHeader, which is
called without a LinkLoader.
So, we would still have to pass linkLoader around, even if this was a member.

 {
-    if (!document.loader())
+    if (!document.loader() || !relAttribute.isLinkPreload())
         return;
 
-    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);
+    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);
-        document.loader()->startPreload(type, linkRequest);
-    }
+    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, linkLoader);
 }
 
 bool LinkLoader::loadLinkFromHeader(const String& headerValue, Document* document, const NetworkHintsInterface& networkHintsInterface, CanLoadResources canLoadResources)
 {
     if (!document)
         return false;
     LinkHeaderSet headerSet(headerValue);
     for (auto& header : headerSet) {
         if (!header.valid() || header.url().isEmpty() || header.rel().isEmpty())
             return false;
 
         LinkRelAttribute relAttribute(header.rel());
         KURL url = document->completeURL(header.url());
         if (canLoadResources == DoNotLoadResources) {
             if (RuntimeEnabledFeatures::linkHeaderEnabled())
                 dnsPrefetchIfNeeded(relAttribute, url, *document, networkHintsInterface, LinkCalledFromHeader);
 
             if (RuntimeEnabledFeatures::linkPreconnectEnabled())
                 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);

[Nate Chapin, 2016/01/13 23:52:23]

Passing nullptr in this case is not immediately obvious (and doesn't work if
preloadIfNeeded becomes a LinkLoader member function). Maybe pass an enum value
indicating whether this preload should have an onload event?

[Yoav Weiss, 2016/01/14 10:10:02]

If preloadIfNeeded would not be static, we wouldn't be able to call it from
here.

         }
         // TODO(yoav): Add more supported headers as needed.
     }
     return true;
 }
 
 bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, CrossOriginAttributeValue crossOrigin, const String& type, const String& as, const KURL& href, Document& document, const NetworkHintsInterface& networkHintsInterface)
 {
     // TODO(yoav): Do all links need to load only after they're in document???
 
     // TODO(yoav): Convert all uses of the CrossOriginAttribute to CrossOriginAttributeValue. crbug.com/486689
     // FIXME(crbug.com/463266): We're ignoring type here. Maybe we shouldn't.
     dnsPrefetchIfNeeded(relAttribute, href, document, networkHintsInterface, LinkCalledFromMarkup);
 
     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()) {
         if (!m_client->shouldLoadLink())
             return false;
         Resource::Type type = Resource::LinkPrefetch;
         if (relAttribute.isLinkSubresource()) {
             type = Resource::LinkSubresource;
             UseCounter::count(document, UseCounter::LinkRelSubresource);
         } else {
@@ skipping 27 matching lines @@
     // atomic (dns prefetch).
     if (m_prerender) {
         m_prerender->cancel();
         m_prerender.clear();
     }
 }
 
 DEFINE_TRACE(LinkLoader)
 {
     visitor->trace(m_prerender);
+    visitor->trace(m_linkPreloadResourceClient);
 }
 
 }