Mojo C++ bindings: Simplify associated interface API.

mojo/public/cpp/bindings/interface_request.h

 // 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_REQUEST_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_REQUEST_H_
 
 #include <string>
 #include <utility>
 
@@ skipping 68 matching lines @@
 
     // Now that the two refer to different objects, they are equivalent if
     // and only if they are both invalid.
     return !is_pending() && !other.is_pending();
   }
 
   void ResetWithReason(uint32_t custom_reason, const std::string& description) {
     if (!handle_.is_valid())
       return;
 
-    base::Optional<DisconnectReason> reason;
-    reason.emplace(custom_reason, description);
-
     Message message =
         PipeControlMessageProxy::ConstructPeerEndpointClosedMessage(
-            kMasterInterfaceId, reason);
+            kMasterInterfaceId, DisconnectReason(custom_reason, description));
     MojoResult result = WriteMessageNew(
         handle_.get(), message.TakeMojoMessage(), MOJO_WRITE_MESSAGE_FLAG_NONE);
     DCHECK_EQ(MOJO_RESULT_OK, result);
 
     handle_.reset();
   }
 
  private:
   ScopedMessagePipeHandle handle_;
 
@@ skipping 67 matching lines @@
 bool FuseInterface(InterfaceRequest<Interface> request,
                    InterfacePtrInfo<Interface> proxy_info) {
   MojoResult result = FuseMessagePipes(request.PassMessagePipe(),
                                        proxy_info.PassHandle());
   return result == MOJO_RESULT_OK;
 }
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_REQUEST_H_