Move mojo::internal::MessageBuilder out of the |internal| namespace.

mojo/tools/message_generator.cc

Index: mojo/tools/message_generator.cc
diff --git a/mojo/tools/message_generator.cc b/mojo/tools/message_generator.cc
index 737fe9b2bffabcc4078aba532cf3dae6ef9f812f..9a791c511785ad25656f2f31127bb7dbb77211df 100644
--- a/mojo/tools/message_generator.cc
+++ b/mojo/tools/message_generator.cc
@@ -39,8 +39,7 @@ void WriteMessageToFile(const Message& message, const base::FilePath& path) {
 // Generates a message of type MessageData. The message uses the name 21,
 // with 4 bytes of payload: 0x9, 0x8, 0x7, 0x6.
 void GenerateMessageDataMessage() {
-  internal::MessageBuilder builder(static_cast<uint32_t>(21),
-                                   static_cast<size_t>(4));
+  MessageBuilder builder(static_cast<uint32_t>(21), static_cast<size_t>(4));
   char* data = static_cast<char*>(builder.buffer()->Allocate(4));
   DCHECK(data);
   data[0] = 9;