Add an end-to-end test for symbolize_trace on macOS.

tracing/bin/run_symbolizer_tests

+#!/usr/bin/env python
+# Copyright 2017 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.
+
+"""
+The symbolizer tests take a long time to run [potentially 5+ minutes each], so
+they are invoked directly from separately from run_py_tests.
+"""
+
+import os
+import sys
+
+_CATAPULT_PATH = os.path.abspath(
+    os.path.join(
+        os.path.dirname(os.path.realpath(__file__)),
+        os.path.pardir,
+        os.path.pardir))
+_TRACING_PATH = os.path.join(_CATAPULT_PATH, 'tracing')
+
+
+def _RunTestsOrDie(top_level_dir):
+  exit_code = run_with_typ.Run(top_level_dir, path=[_TRACING_PATH],
+                               suffixes=['*_test_slow.py'])
+  if exit_code:
+    sys.exit(exit_code)
+
+
+def _AddToPathIfNeeded(path):
+  if path not in sys.path:
+    sys.path.insert(0, path)
+
+
+if __name__ == '__main__':
+  _AddToPathIfNeeded(_CATAPULT_PATH)
+
+  from catapult_build import run_with_typ
+  _RunTestsOrDie(os.path.join(_TRACING_PATH, 'tracing', 'extras', 'symbolizer'))
+  sys.exit(0)