Making the Mojo Channel Messages legacy mode dynamic.

mojo/edk/system/channel_unittest.cc

 // Copyright 2017 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/channel.h"
 #include "base/memory/ptr_util.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace mojo {
@@ skipping 48 matching lines @@
   // Notify that an error has occured and the Channel will cease operation.
   void OnChannelError() override {}
 
  private:
   size_t payload_size_ = 0;
   std::unique_ptr<char[]> payload_;
 };
 
 Channel::MessagePtr CreateDefaultMessage(bool legacy_message) {
   const size_t payload_size = 100;
+  Channel::Message::SetUseLegacyTransportProtocol(legacy_message);

[Ken Rockot(use gerrit already), 2017/03/15 17:59:31]

Hmm. This isn't really safe. Messages can be created at any time from any thread
(for e.g. propagating internal ports events). Might be OK for now the way these
tests work, but it seems too subtle, and it also makes it impossible to enforce
the otherwise useful DCHECK in my other comment.

Can we just leave this code alone since the constructor which takes a message
type is still usable?

[Jay Civelli, 2017/03/15 18:14:09]

Sure, I was actually hesitant with that changed (I wanted to check that
SetUseLegacyTransportProtocol really propagates to the message).

   Channel::MessagePtr message = base::MakeUnique<Channel::Message>(
-      payload_size, 0,
-      legacy_message ? Channel::Message::MessageType::NORMAL_LEGACY
-                     : Channel::Message::MessageType::NORMAL);
+      payload_size, 0);
   char* payload = static_cast<char*>(message->mutable_payload());
   for (size_t i = 0; i < payload_size; i++) {
     payload[i] = static_cast<char>(i);
   }
   return message;
 }
 
 void TestMemoryEqual(const void* data1,
                      size_t data1_size,
                      const void* data2,
@@ skipping 85 matching lines @@
                                           &next_read_size_hint));
 
   TestMemoryEqual(message->payload(), message->payload_size(),
                   channel_delegate.GetReceivedPayload(),
                   channel_delegate.GetReceivedPayloadSize());
 }
 
 }  // namespace
 }  // namespace edk
 }  // namespace mojo