Add GN bootstrap step to continuous integration

testing/scripts/gn_bootstrap.py

 #!/usr/bin/env python
 # Copyright 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 json
 import os
 import sys
 
 
 import common
 
 
 def main_run(args):
   with common.temporary_file() as tempfile_path:
     rc = common.run_command([
-        os.path.join(common.SRC_DIR, 'android_webview', 'tools',
-                     'webview_licenses.py'),
-        'scan',
+        os.path.join(common.SRC_DIR, 'tools', 'gn',
+                     'bootstrap', 'bootstrap.py'),
+        # Do not interfere with "mainline" build directory.
+        '--temp-build-dir',
+        # Bots are still using Ubuntu Precise and gcc 4.6. We need
+        # C++11 support provided by bundled clang.
+        '--use-bundled-clang',
         '--json', tempfile_path
     ])
 
     with open(tempfile_path) as f:
-      results = json.load(f)
+      bootstrap_results = json.load(f)
 
   json.dump({
       'valid': True,
-      'failures': results,
+      'failures': bootstrap_results,
   }, args.output)
 
   return rc
 
 
 def main_compile_targets(args):
   json.dump([], args.output)
 
 
 if __name__ == '__main__':
   funcs = {
     'run': main_run,
     'compile_targets': main_compile_targets,
   }
   sys.exit(common.run_script(sys.argv[1:], funcs))