Move more Mojo bindings helpers out of internal namespace

mojo/public/cpp/bindings/message.h

Index: mojo/public/cpp/bindings/message.h
diff --git a/mojo/public/cpp/bindings/message.h b/mojo/public/cpp/bindings/message.h
index 87a6f58a43314b07c0fbaebbbb2be6a5276f3b5e..e758432b9a953d5131d53c10509c71b1d4a7f52f 100644
--- a/mojo/public/cpp/bindings/message.h
+++ b/mojo/public/cpp/bindings/message.h
@@ -26,6 +26,10 @@ namespace mojo {
 // followed by payload.
 class Message {
  public:
+  static const uint32_t kFlagExpectsResponse = 1 << 0;
+  static const uint32_t kFlagIsResponse = 1 << 1;
+  static const uint32_t kFlagIsSync = 1 << 2;
+
   Message();
   ~Message();