Make PacketReader/PacketWriter interfaces async-only.

blimp/net/packet_writer.h

Index: blimp/net/packet_writer.h
diff --git a/blimp/net/packet_writer.h b/blimp/net/packet_writer.h
index e5dbb9a1d53d1543a02c478aad118f735f466702..8c7b9ca7fb46c324d0c15efeb1bad7dadfda8415 100644
--- a/blimp/net/packet_writer.h
+++ b/blimp/net/packet_writer.h
@@ -21,14 +21,11 @@ class BLIMP_NET_EXPORT PacketWriter {
  public:
   virtual ~PacketWriter() {}
 
-  // Writes a packet of at least one byte in size to a connection.
-  //
-  // Returns net::OK or an error code if the operation executed successfully.
-  // Returns ERR_IO_PENDING if the operation will be executed asynchronously.
-  //     |cb| is later invoked with net::OK or an error code.
-  // An error code indicates that caller should stop using this writer.
-  virtual int WritePacket(scoped_refptr<net::DrainableIOBuffer> data,
-                          const net::CompletionCallback& callback) = 0;
+  // Invokes |cb| with net::OK if the write operation executed successfully.
+  // All other values indicate unrecoverable errors.
+  // |callback| must not be invoked if |this| is deleted.
+  virtual void WritePacket(scoped_refptr<net::DrainableIOBuffer> data,
+                           const net::CompletionCallback& callback) = 0;
 };
 
 }  // namespace blimp