Removal of rel=preload link elements should stop the download.

third_party/WebKit/Source/core/loader/LinkPreloadResourceClients.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef LinkPreloadResourceClients_h
 #define LinkPreloadResourceClients_h
 
 #include "core/fetch/CSSStyleSheetResource.h"
 #include "core/fetch/FontResource.h"
 #include "core/fetch/ImageResourceClient.h"
+#include "core/fetch/ResourceLoader.h"
 #include "core/fetch/ResourceOwner.h"
 #include "core/fetch/ScriptResource.h"
 #include "core/fetch/StyleSheetResourceClient.h"
 
 namespace blink {
 
 class LinkLoader;
 
 class LinkPreloadResourceClient : public NoBaseWillBeGarbageCollectedFinalized<LinkPreloadResourceClient> {
 public:
     virtual ~LinkPreloadResourceClient() { }
 
     void triggerEvents(const Resource*);
 
+    virtual void cancel() = 0;
+
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
         visitor->trace(m_loader);
     }
 
 protected:
     LinkPreloadResourceClient(LinkLoader* loader)
         : m_loader(loader)
     {
         ASSERT(loader);
@@ skipping 19 matching lines @@
         ASSERT(this->resource() == resource);
         triggerEvents(resource);
     }
 
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
         LinkPreloadResourceClient::trace(visitor);
         ResourceOwner<ScriptResource, ScriptResourceClient>::trace(visitor);
     }
 
+    void cancel() override
+    {
+        if (resource() && resource()->loader())
+            resource()->loader()->cancel();

[Nate Chapin, 2016/01/21 19:03:50]

This will cancel the load even if the preload is now being used by a real load.
That seems wrong?

[Yoav Weiss, 2016/01/21 21:51:21]

yeah. changed to clearResource()

+    }
+
 private:
     LinkPreloadScriptResourceClient(LinkLoader* loader, ScriptResource* resource)
         : LinkPreloadResourceClient(loader)
     {
         setResource(resource);
     }
 };
 
 class LinkPreloadStyleResourceClient: public LinkPreloadResourceClient, public ResourceOwner<CSSStyleSheetResource, StyleSheetResourceClient> {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(LinkPreloadStyleResourceClient);
@@ skipping 11 matching lines @@
         ASSERT(this->resource() == resource);
         triggerEvents(static_cast<const Resource*>(resource));
     }
 
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
         LinkPreloadResourceClient::trace(visitor);
         ResourceOwner<CSSStyleSheetResource, StyleSheetResourceClient>::trace(visitor);
     }
 
+    void cancel() override
+    {
+        if (resource() && resource()->loader())
+            resource()->loader()->cancel();
+    }
+
 private:
     LinkPreloadStyleResourceClient(LinkLoader* loader, CSSStyleSheetResource* resource)
         : LinkPreloadResourceClient(loader)
     {
         setResource(resource);
     }
 };
 
 }
 
 #endif // LinkPreloadResourceClients_h