Add a Mojo example apptest that runs in mojo_shell.

mojo/examples/test/example_service_impl.h

Index: mojo/examples/test/example_service_impl.h
diff --git a/mojo/examples/test/example_service_impl.h b/mojo/examples/test/example_service_impl.h
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+++ b/mojo/examples/test/example_service_impl.h
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+// Copyright 2014 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 MOJO_EXAMPLES_TEST_EXAMPLE_SERVICE_IMPL_H_
+#define MOJO_EXAMPLES_TEST_EXAMPLE_SERVICE_IMPL_H_
+
+#include "mojo/examples/test/example_service.mojom.h"
+#include "mojo/public/cpp/system/macros.h"
+
+namespace mojo {
+
+class ApplicationConnection;
+
+class ExampleServiceImpl : public InterfaceImpl<ExampleService> {
+ public:
+ explicit ExampleServiceImpl(ApplicationConnection* connection);
+ virtual ~ExampleServiceImpl();
+
+ protected:
+  // InterfaceImpl<ExampleService> overrides.
+  virtual void Echo(
+    const String& to_echo,
+    const Callback<void(String)>& callback) MOJO_OVERRIDE;
+  virtual void Ping(uint16_t ping_value) MOJO_OVERRIDE;
+
+ private:
+  MOJO_DISALLOW_COPY_AND_ASSIGN(ExampleServiceImpl);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_EXAMPLES_TEST_EXAMPLE_SERVICE_IMPL_H_