Cancel the request when URLLoader is gone

content/browser/service_worker/service_worker_fetch_dispatcher.cc

 // Copyright 2014 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.
 
 #include "content/browser/service_worker/service_worker_fetch_dispatcher.h"
 
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 28 matching lines @@
 
 // This class wraps a mojo::AssociatedInterfacePtr<URLLoader>. It also is a
 // URLLoader implementation and delegates URLLoader calls to the wrapped loader.
 class DelegatingURLLoader final : public mojom::URLLoader {
  public:
   explicit DelegatingURLLoader(mojom::URLLoaderAssociatedPtr loader)
       : binding_(this), loader_(std::move(loader)) {}
   ~DelegatingURLLoader() override {}
 
   void FollowRedirect() override { loader_->FollowRedirect(); }
-  void Cancel() override { loader_->Cancel(); }
 
   mojom::URLLoaderPtr CreateInterfacePtrAndBind() {
-    return binding_.CreateInterfacePtrAndBind();
+    auto p = binding_.CreateInterfacePtrAndBind();
+    // This unretained pointer is safe, because |binding_| is owned by |this|
+    // and the callback will never be called after |this| is destroyed.
+    binding_.set_connection_error_handler(
+        base::Bind(&DelegatingURLLoader::Cancel, base::Unretained(this)));
+    return p;
   }
 
  private:
+  void Cancel() { loader_ = nullptr; }

[horo, 2016/11/09 10:02:08]

Please add comments.

  // Called when the mojom::URLLoaderPtr in the service worker is deleted.
  void Cancel() {
    // Clears |loader_| to call MojoAsyncResourceHandler::Cancel() and cancel
    // the request if it is still ongoing.
    loader_ = nullptr;
  }

[yhirano, 2016/11/11 04:22:22]

Done.

+
   mojo::Binding<mojom::URLLoader> binding_;
   mojom::URLLoaderAssociatedPtr loader_;
 
   DISALLOW_COPY_AND_ASSIGN(DelegatingURLLoader);
 };
 
 // This class wraps a mojo::InterfacePtr<URLLoaderClient>. It also is a
 // URLLoaderClient implementation and delegates URLLoaderClient calls to the
 // wrapped client.
 class DelegatingURLLoaderClient final : public mojom::URLLoaderClient {
@@ skipping 368 matching lines @@
 }
 
 ServiceWorkerMetrics::EventType ServiceWorkerFetchDispatcher::GetEventType()
     const {
   if (request_->fetch_type == ServiceWorkerFetchType::FOREIGN_FETCH)
     return ServiceWorkerMetrics::EventType::FOREIGN_FETCH;
   return ResourceTypeToEventType(resource_type_);
 }
 
 }  // namespace content