Add a basic browser to mash that uses the navigation service.

mash/browser/main.cc

Index: mash/browser/main.cc
diff --git a/mash/browser/main.cc b/mash/browser/main.cc
new file mode 100644
index 0000000000000000000000000000000000000000..8105d7ac662c419f17bbac444e450f8659322ee7
--- /dev/null
+++ b/mash/browser/main.cc
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+// Copyright 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.
+
+#include "mash/browser/browser.h"
+#include "mojo/public/c/system/main.h"
+#include "services/shell/public/cpp/application_runner.h"
+
+MojoResult MojoMain(MojoHandle shell_handle) {
+  shell::ApplicationRunner runner(new mash::browser::Browser);
+  return runner.Run(shell_handle);
+}