🎣 Reland of Make Android .build_configs aware of prebuilts and java sources

build/android/gyp/javac.py

 #!/usr/bin/env python
 #
 # Copyright 2013 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 optparse
 import os
 import shutil
 import re
@@ skipping 306 matching lines @@
   for arg in options.java_srcjars:
     java_srcjars += build_utils.ParseGypList(arg)
   options.java_srcjars = java_srcjars
 
   if options.src_gendirs:
     options.src_gendirs = build_utils.ParseGypList(options.src_gendirs)
 
   options.javac_includes = build_utils.ParseGypList(options.javac_includes)
   options.jar_excluded_classes = (
       build_utils.ParseGypList(options.jar_excluded_classes))
-  return options, args
+
+  java_files = []
+  for arg in args:
+    # Interpret a path prefixed with @ as a file containing a list of sources.
+    if arg.startswith('@'):
+      with open(arg[1:]) as f:
+        java_files.extend(l.strip() for l in f)
+    else:
+      java_files.append(arg)
+
+  return options, java_files
 
 
 def main(argv):
   colorama.init()
 
   argv = build_utils.ExpandFileArgs(argv)
   options, java_files = _ParseOptions(argv)
 
   if options.src_gendirs:
     java_files += build_utils.FindInDirectories(options.src_gendirs, '*.java')
@@ skipping 70 matching lines @@
       options,
       input_paths=input_paths,
       input_strings=javac_cmd,
       output_paths=output_paths,
       force=force,
       pass_changes=True)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))