Make sure 'mb analyze' handles "all" correctly as a target.

tools/mb/mb.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.
 
 """MB - the Meta-Build wrapper around GYP and GN
 
 MB is a wrapper script for GYP and GN that can be used to generate build files
 for sets of canned configurations and analyze them.
 """
@@ skipping 398 matching lines @@
       self.Print()
 
     output_path = self.args.output_path[0]
 
     # Bail out early if a GN file was modified, since 'gn refs' won't know
     # what to do about it.
     if any(f.endswith('.gn') or f.endswith('.gni') for f in inp['files']):
       self.WriteJSON({'status': 'Found dependency (all)'}, output_path)
       return 0
 
+    # TODO: Because of the --type=executable filter below, we don't detect
+    # when files will cause 'all' or 'gn_all' or similar targets to be
+    # dirty. We need to figure out how to handle that properly, but for
+    # now we can just bail out early.
+    if 'gn_all' in inp['targets'] or 'all' in inp['targets']:
+      self.WriteJSON({'status': 'Found dependency (all)'}, output_path)
+      return 0
+
     all_needed_targets = set()
     ret = 0
     for f in inp['files']:
       cmd = self.GNCmd('refs', self.args.path[0]) + [
              '//' + f, '--type=executable', '--all', '--as=output']
       ret, out, _ = self.Run(cmd)
       if ret:
         self.WriteFailureAndRaise('gn refs returned %d: %s' % (ret, out),
                                   output_path)
 
@@ skipping 111 matching lines @@
 
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv[1:]))
   except MBErr as e:
     print(e)
     sys.exit(1)
   except KeyboardInterrupt:
     print("interrupted, exiting", stream=sys.stderr)
     sys.exit(130)