[inspector_protocol] support fall through and moveable Maybe

lib/BackendCallback_h.template

Index: lib/BackendCallback_h.template
diff --git a/lib/BackendCallback_h.template b/lib/BackendCallback_h.template
deleted file mode 100644
index 3c8fc15b3216e53c982f478fd315e50f83b63358..0000000000000000000000000000000000000000
--- a/lib/BackendCallback_h.template
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright (c) 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef {{"_".join(config.protocol.namespace)}}_BackendCallback_h
-#define {{"_".join(config.protocol.namespace)}}_BackendCallback_h
-
-//#include "Forward.h"
-
-{% for namespace in config.protocol.namespace %}
-namespace {{namespace}} {
-{% endfor %}
-
-class {{config.lib.export_macro}} BackendCallback {
-public:
-    virtual ~BackendCallback() { }
-    virtual void sendFailure(const ErrorString&) = 0;
-};
-
-{% for namespace in config.protocol.namespace %}
-} // namespace {{namespace}}
-{% endfor %}
-
-#endif // !defined({{"_".join(config.protocol.namespace)}}_BackendCallback_h)