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

build/android/gyp/javac.py

Index: build/android/gyp/javac.py
diff --git a/build/android/gyp/javac.py b/build/android/gyp/javac.py
index 6c91424710039d58c70f0f821670b0c9e01cfcfc..7b5264d3794f56996b7f478144c67a7a52fb0810 100755
--- a/build/android/gyp/javac.py
+++ b/build/android/gyp/javac.py
@@ -324,7 +324,17 @@ def _ParseOptions(argv):
   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):