Cancel loading when body stream reader is detached.

content/child/shared_memory_data_consumer_handle.h

 // Copyright 2015 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 CONTENT_CHILD_SHARED_MEMORY_DATA_CONSUMER_HANDLE_H_
 #define CONTENT_CHILD_SHARED_MEMORY_DATA_CONSUMER_HANDLE_H_
 
+#include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "content/common/content_export.h"
 #include "content/public/child/request_peer.h"
 #include "third_party/WebKit/public/platform/WebDataConsumerHandle.h"
 
 namespace content {
 
 // This class is a WebDataConsumerHandle that accepts RequestPeer::ReceivedData.
 class CONTENT_EXPORT SharedMemoryDataConsumerHandle final
@@ skipping 34 matching lines @@
                              Flags flags,
                              size_t* available);
     virtual Result endRead(size_t readSize);
 
    private:
     scoped_refptr<Context> context_;
 
     DISALLOW_COPY_AND_ASSIGN(ReaderImpl);
  };
 
+  // Creates a handle and a writer associated with the handle. The created
+  // writer should be used on the calling thread.
   SharedMemoryDataConsumerHandle(BackpressureMode mode,
                                  scoped_ptr<Writer>* writer);
+  // |on_clear| will be called asynchronously on the calling thread when both
+  // the associated handle and the reader are destructed.

[hiroshige, 2015/06/22 18:23:16]

Better name (here and related method/member names) is preferred for |on_clear_|
because |on_clear_| looks like a callback for Clear() but actually a callback
for Handle/Reader-initiated Clear().

How about:
- modifying this comment to "... when the body data stream is detached from the
reader side, i.e. when both the associated handle and the reader are
destructed."
- s/on_clear_/on_detach_from_reader_side/g (also do similar for related names)

[yhirano, 2015/06/23 05:28:38]

Done.

+  // The callback will be reset in the internal context when |Close| or |Error|
+  // on the writer is called.

[hiroshige, 2015/06/22 18:23:16]

How about "will be reset in the internal context when the body data stream is
detached from the writer side, i.e. |Close| or |Error| on the writer is called."
for symmetry?

[yhirano, 2015/06/23 05:28:38]

Done.

+  SharedMemoryDataConsumerHandle(BackpressureMode mode,
+                                 const base::Closure& on_clear,
+                                 scoped_ptr<Writer>* writer);
   virtual ~SharedMemoryDataConsumerHandle();
 
   scoped_ptr<Reader> ObtainReader(Client* client);
 
  private:
   virtual ReaderImpl* obtainReaderInternal(Client* client);
   const char* debugName() const override;
 
   scoped_refptr<Context> context_;
 
   DISALLOW_COPY_AND_ASSIGN(SharedMemoryDataConsumerHandle);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_SHARED_MEMORY_DATA_CONSUMER_HANDLE_H_