Add GN bootstrap step to continuous integration

testing/scripts/gn_bootstrap.py

Index: testing/scripts/gn_bootstrap.py
diff --git a/testing/scripts/webview_licenses.py b/testing/scripts/gn_bootstrap.py
similarity index 62%
copy from testing/scripts/webview_licenses.py
copy to testing/scripts/gn_bootstrap.py
index 255c62e993111f82f0d47d2445ed89312ea28c16..86a986702d30b2a867a4321330d1ce30c61e1e5e 100755
--- a/testing/scripts/webview_licenses.py
+++ b/testing/scripts/gn_bootstrap.py
@@ -14,18 +14,22 @@ 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