Added GPU stress test with multiple tabs in one single window.

content/test/gpu/run_gpu_stress_tests

 #!/usr/bin/env python
-# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Copyright (c) 2013 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.
+
+"""This script runs tests to verify that the GPU is working properly."""
+
 import os
 import sys
 
+import gpu_stress_tests
 from telemetry.test import gtest_testrunner
 from telemetry.test import run_tests
 
 if __name__ == '__main__':
   top_level_dir = os.path.abspath(os.path.dirname(__file__))
   runner = gtest_testrunner.GTestTestRunner(print_result_after_run=False)
-  start_dir = 'telemetry'
-  ret = run_tests.Main(sys.argv[1:], start_dir, top_level_dir, runner)
+  ret = run_tests.Main(sys.argv[1:], 'gpu_stress_tests', top_level_dir, runner)
 
   if runner.result:
     runner.result.PrintSummary()
     sys.exit(min(ret + runner.result.num_errors, 255))
   else:
     sys.exit(ret)