[Telemetry] Add an example for adding an end to end Telemetry benchmark

tools/telemetry/examples/run_benchmark

+#!/usr/bin/env python
+# Copyright (c) 2015 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.
+import os
+import sys
+
+sys.path.append(os.path.join(os.path.dirname(__file__), '..'))
+from telemetry import benchmark_runner
+
+def main():
+  top_level_dir = os.path.dirname(__file__)
+  config = benchmark_runner.ProjectConfig(
+      top_level_dir=top_level_dir,
+      benchmark_dirs=[os.path.join(top_level_dir, 'benchmarks')])
+  return benchmark_runner.main(config)
+
+if __name__ == '__main__':
+  sys.exit(main())