[mojo-edk] Fix uninitialized reads in EDK dispatchers

mojo/edk/system/data_pipe_consumer_dispatcher.cc

 // Copyright 2013 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 "mojo/edk/system/data_pipe_consumer_dispatcher.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 507 matching lines @@
   size_t previous_bytes_available = bytes_available_;
 
   ports::PortStatus port_status;
   if (node_controller_->node()->GetStatus(control_port_, &port_status) !=
           ports::OK ||
       !port_status.receiving_messages) {
     DVLOG(1) << "Data pipe consumer " << pipe_id_ << " is aware of peer closure"
              << " [control_port=" << control_port_.name() << "]";
 
     peer_closed_ = true;
-  }
-
-  if (port_status.has_messages && !in_transit_) {
+  } else if (port_status.has_messages && !in_transit_) {

[Anand Mistry (off Chromium), 2016/05/04 00:50:03]

I'm still pushing back on this construct because I think it's terrible. It may
be fine for us that are very familiar with C++ and this code base, but it's
going to confuse anyone that's new to this.

Basically, my opinion is that it should be possible to evaluate any branch of an
if block independently. There shouldn't be a sequential dependency in the
evaluation of the branch conditions. If you need a result in multiple branches,
pull it out of the if block.

Sorry, but that's my opinion on this.

[Ken Rockot(use gerrit already), 2016/05/04 02:57:05]

done

     ports::ScopedMessage message;
     do {
       int rv = node_controller_->node()->GetMessageIf(control_port_, nullptr,
                                                       &message);
       if (rv != ports::OK)
         peer_closed_ = true;
       if (message) {
         const DataPipeControlMessage* m =
             static_cast<const DataPipeControlMessage*>(
                 message->payload_bytes());
@@ skipping 21 matching lines @@
   }
 
   if (peer_closed_ != was_peer_closed ||
       bytes_available_ != previous_bytes_available) {
     awakable_list_.AwakeForStateChange(GetHandleSignalsStateNoLock());
   }
 }
 
 }  // namespace edk
 }  // namespace mojo