Cancel loading when body stream reader is detached.

content/child/shared_memory_data_consumer_handle.h

Index: content/child/shared_memory_data_consumer_handle.h
diff --git a/content/child/shared_memory_data_consumer_handle.h b/content/child/shared_memory_data_consumer_handle.h
index 6d74178f5cda317e5fdc1e0c6e85e5d92756ad25..cd760acd209784b2e30f35e7fa3ef3ec62ed48ed 100644
--- a/content/child/shared_memory_data_consumer_handle.h
+++ b/content/child/shared_memory_data_consumer_handle.h
@@ -5,6 +5,7 @@
 #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"
@@ -59,8 +60,17 @@ class CONTENT_EXPORT SharedMemoryDataConsumerHandle final
     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);