Fix an issue that tools/license.py fails when BUILD.gn is not directly

tools/licenses.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Utility for checking and processing licensing information in third_party
 directories.
 
 Usage: licenses.py <command>
 
 Commands:
   scan     scan third_party directories, verifying that we have licensing info
   credits  generate about:credits on stdout
 
 (You can also import this as a module.)
 """
 
 import argparse
 import cgi
 import os
 import shutil
+import re
 import subprocess
 import sys
 import tempfile
 
 # TODO(agrieve): Move build_utils.WriteDepFile into a non-android directory.
 _REPOSITORY_ROOT = os.path.dirname(os.path.dirname(__file__))
 sys.path.append(os.path.join(_REPOSITORY_ROOT, 'build/android/gyp/util'))
 import build_utils
 
 
@@ skipping 441 matching lines @@
     elif sys.platform == 'darwin':
         subdir = 'mac'
     elif sys.platform == 'win32':
         subdir, exe = 'win', 'gn.exe'
     else:
         raise RuntimeError("Unsupported platform '%s'." % sys.platform)
 
     return os.path.join(_REPOSITORY_ROOT, 'buildtools', subdir, exe)
 
 
+def GetThirdPartyDepsFromGNDepsOutput(gn_deps):
+    """Returns third_party/foo directories given the output of "gn desc deps".
+
+    Note that it always returns the direct sub-directory of third_party
+    where README.chromium and LICENSE files are, so that it can be passed to
+    ParseDir(). e.g.:
+        .../third_party/cld_3/src/src/BUILD.gn -> .../third_party/cld_3
+    """
+    third_party_deps = set()
+    for build_dep in gn_deps.split():
+        m = re.search(r'^(.+/third_party/[^/]+)/(.+/)?BUILD\.gn$', build_dep)
+        if m:
+            third_party_deps.add(m.group(1))
+    return third_party_deps
+
+
 def FindThirdPartyDeps(gn_out_dir, gn_target):
     if not gn_out_dir:
         raise RuntimeError("--gn-out-dir is required if --gn-target is used.")
 
     # Generate gn project in temp directory and use it to find dependencies.
     # Current gn directory cannot be used when we run this script in a gn action
     # rule, because gn doesn't allow recursive invocations due to potential side
     # effects.
     tmp_dir = None
     try:
         tmp_dir = tempfile.mkdtemp(dir = gn_out_dir)
         shutil.copy(os.path.join(gn_out_dir, "args.gn"), tmp_dir)
         subprocess.check_output([_GnBinary(), "gen", tmp_dir])
         gn_deps = subprocess.check_output([
             _GnBinary(), "desc", tmp_dir, gn_target,
             "deps", "--as=buildfile", "--all"])
     finally:
         if tmp_dir and os.path.exists(tmp_dir):
             shutil.rmtree(tmp_dir)
 
-    third_party_deps = set()
-    for build_dep in gn_deps.split():
-        if ("third_party" in build_dep and
-                os.path.basename(build_dep) == "BUILD.gn"):
-            third_party_deps.add(os.path.dirname(build_dep))
-    return third_party_deps
+    return GetThirdPartyDepsFromGNDepsOutput(gn_deps)
 
 
 def ScanThirdPartyDirs(root=None):
     """Scan a list of directories and report on any problems we find."""
     if root is None:
       root = os.getcwd()
     third_party_dirs = FindThirdPartyDirsWithFiles(root)
 
     errors = []
     for path in sorted(third_party_dirs):
@@ skipping 187 matching lines @@
         if not GenerateLicenseFile(
                 args.output_file, args.gn_out_dir, args.gn_target):
             return 1
     else:
         print __doc__
         return 1
 
 
 if __name__ == '__main__':
   sys.exit(main())