Keep DocumentThreadableLoader for keepalive requests

...in order to make the logic work after frame detach.
This CL also removes Resource::SetDetachable which is no longer needed.

Bug: 836641
Change-Id: I6ebc978021cafa9a6337afab5de29532fc28c4c1
Reviewed-on: https://chromium-review.googlesource.com/1027210Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553526}

third_party/blink/renderer/core/loader/document_threadable_loader.cc

@@ -146,6 +146,27 @@ class EmptyDataHandle final : public WebDataConsumerHandle {
 
 }  // namespace
 
+// DetachedClient is a ThreadableLoaderClient for a "detached"
+// DocumentThreadableLoader. It's for fetch requests with keepalive set, so
+// it keeps itself alive during loading.
+class DocumentThreadableLoader::DetachedClient final
+    : public GarbageCollectedFinalized<DetachedClient>,
+      public ThreadableLoaderClient {
+ public:
+  DetachedClient() : self_keep_alive_(this) {}
+  ~DetachedClient() override {}
+
+  void DidFinishLoading(unsigned long identifier, double finish_time) override {
+    self_keep_alive_.Clear();
+  }
+  void DidFail(const ResourceError&) override { self_keep_alive_.Clear(); }
+  void DidFailRedirectCheck() override { self_keep_alive_.Clear(); }
+  void Trace(Visitor* visitor) {}
+
+ private:
+  SelfKeepAlive<DetachedClient> self_keep_alive_;
+};
+
 // Max number of CORS redirects handled in DocumentThreadableLoader. Same number
 // as net/url_request/url_request.cc, and same number as
 // https://fetch.spec.whatwg.org/#concept-http-fetch, Step 4.
@@ -546,9 +567,9 @@ void DocumentThreadableLoader::Cancel() {
 
 void DocumentThreadableLoader::Detach() {
   Resource* resource = GetResource();
-  if (resource)
-    resource->SetDetachable();
-  Clear();
+  if (!resource)
+    return;
+  client_ = new DetachedClient();
 }
 
 void DocumentThreadableLoader::SetDefersLoading(bool value) {

third_party/blink/renderer/core/loader/document_threadable_loader.h

@@ -88,6 +88,7 @@ class CORE_EXPORT DocumentThreadableLoader final : public ThreadableLoader,
   void Trace(blink::Visitor*) override;
 
  private:
+  class DetachedClient;
   enum BlockingBehavior { kLoadSynchronously, kLoadAsynchronously };
 
   static std::unique_ptr<ResourceRequest> CreateAccessControlPreflightRequest(

third_party/blink/renderer/platform/loader/fetch/resource.cc

@@ -704,7 +704,7 @@ void Resource::DidRemoveClientOrObserver() {
 }
 
 void Resource::AllClientsAndObserversRemoved() {
-  if (loader_ && !detachable_)
+  if (loader_)
     loader_->ScheduleCancel();
 }
 

third_party/blink/renderer/platform/loader/fetch/resource.h

@@ -166,9 +166,6 @@ class PLATFORM_EXPORT Resource : public GarbageCollectedFinalized<Resource>,
   // base::SingleThreadTaskRunner is unused.
   void AddClient(ResourceClient*, base::SingleThreadTaskRunner*);
   void RemoveClient(ResourceClient*);
-  // Once called, this resource will not be canceled until load finishes
-  // even if associated with no client.
-  void SetDetachable() { detachable_ = true; }
 
   // If this Resource is already finished when AddFinishObserver is called, the
   // ResourceFinishObserver will be notified asynchronously by a task scheduled
@@ -521,7 +518,6 @@ class PLATFORM_EXPORT Resource : public GarbageCollectedFinalized<Resource>,
   bool is_add_remove_client_prohibited_;
   bool is_revalidation_start_forbidden_ = false;
   bool is_unused_preload_ = false;
-  bool detachable_ = false;
 
   ResourceIntegrityDisposition integrity_disposition_;
   SubresourceIntegrity::ReportInfo integrity_report_info_;