Making the Mojo Channel Messages legacy mode dynamic.

mojo/edk/system/channel_unittest.cc

Index: mojo/edk/system/channel_unittest.cc
diff --git a/mojo/edk/system/channel_unittest.cc b/mojo/edk/system/channel_unittest.cc
index ce2c804d55f4bf289a67535c54229fa35d2bed49..74d447ff4d2dd4fd4b065a197db980dc4b3dc00c 100644
--- a/mojo/edk/system/channel_unittest.cc
+++ b/mojo/edk/system/channel_unittest.cc
@@ -66,10 +66,9 @@ class MockChannelDelegate : public Channel::Delegate {
 
 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);