move SkMessageBus::Get out of header

tests/MessageBusTest.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMessageBus.h"
 #include "Test.h"
 
-namespace {
-
 struct TestMessage {
     int x;
     float y;
 };
-
-}  // namespace
+DECLARE_SKMESSAGEBUS_MESSAGE(TestMessage)
 
 DEF_TEST(MessageBus, r) {
     // Register two inboxes to receive all TestMessages.
     SkMessageBus<TestMessage>::Inbox inbox1, inbox2;
 
     // Send two messages.
     const TestMessage m1 = { 5, 4.2f };
     const TestMessage m2 = { 6, 4.3f };
     SkMessageBus<TestMessage>::Post(m1);
     SkMessageBus<TestMessage>::Post(m2);
@@ skipping 18 matching lines @@
 
     // Over all this time, inbox2 should have piled up 3 messages.
     inbox2.poll(&messages);
     REPORTER_ASSERT(r, 3 == messages.count());
     REPORTER_ASSERT(r, 5 == messages[0].x);
     REPORTER_ASSERT(r, 6 == messages[1].x);
     REPORTER_ASSERT(r, 1 == messages[2].x);
 }
 
 // Multithreaded tests tbd.