Make checkperms.py look for shebang.

This should enable removing most (if not all) of the whitelist.

R=thestig@chromium.org
BUG=
TEST=


Review URL: http://codereview.chromium.org/10083003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@132258 0039d316-1c4b-4281-b951-d872f2087c98

tools/checkperms/checkperms.py

@@ -177,6 +177,12 @@ def CheckFile(file_path):
     return 'Failed to stat file: %s' % e
 
   if EXECUTABLE_PERMISSION & st_mode:
+    # Look if the file starts with #!/
+    with open(file_path, 'rb') as f:
+      if f.read(3) == '#!/':
+        # That's fine.
+        return None
+    # TODO(maruel): Check that non-executable file do not start with a shebang.
     error = 'Contains executable permission'
     if VERBOSE:
       return '%s: %06o' % (error, st_mode)