Making the Mojo Channel Messages legacy mode dynamic.

mojo/edk/embedder/embedder.h

Index: mojo/edk/embedder/embedder.h
diff --git a/mojo/edk/embedder/embedder.h b/mojo/edk/embedder/embedder.h
index 97258e52f61d535bcf96f95be25ecf659fbefb56..c89039cea856945d5702c311a1e013cdb15ec7ea 100644
--- a/mojo/edk/embedder/embedder.h
+++ b/mojo/edk/embedder/embedder.h
@@ -74,6 +74,13 @@ MOJO_SYSTEM_IMPL_EXPORT void Init();
 MOJO_SYSTEM_IMPL_EXPORT void SetDefaultProcessErrorCallback(
     const ProcessErrorCallback& callback);
 
+// Used to select whether mojo:edk::Channel should use the legacy or normal
+// header.
+// TODO(jcivelli): http://crbug.com/695645 remove this when legacy mode is not
+//                 in use anymore.
+MOJO_SYSTEM_IMPL_EXPORT void SetUseLegacyTransportProtocol(
+    bool use_legacy_protocol);
+
 // Basic functions -------------------------------------------------------------
 
 // The functions in this section are available once |Init()| has been called.