Improve CLI interface of C++ enums to Java generator

build/config/android/rules.gni

Index: build/config/android/rules.gni
diff --git a/build/config/android/rules.gni b/build/config/android/rules.gni
index 8ca064248e268036fbc7c1bc9231cca055da7fa0..864d41fdfe5e641a1ecc41cd01d7261f05220ada 100644
--- a/build/config/android/rules.gni
+++ b/build/config/android/rules.gni
@@ -335,8 +335,8 @@ template("java_cpp_template") {
 #
 #   outputs: list of outputs, relative to the output_dir. These paths are
 #     verified at build time by the script. To get the list programatically run:
-#       python build/android/gyp/java_cpp_enum.py --output_dir=. \
-#         --print_output_only path/to/header/file.h
+#       python build/android/gyp/java_cpp_enum.py \
+#         --print_output_only . path/to/header/file.h
 #
 # Example
 #   java_cpp_enum("foo_generated_enum") {
@@ -366,16 +366,14 @@ template("java_cpp_enum") {
     outputs =
         get_path_info(rebase_path(invoker.outputs, ".", gen_dir), "abspath")
 
-    args = [
-      "--output_dir",
-      rebase_path(gen_dir, root_build_dir),
-    ]
+    args = []
     foreach(output, rebase_path(outputs, root_build_dir)) {
       args += [
         "--assert_file",
         output,
       ]
     }
+    args += [ rebase_path(gen_dir, root_build_dir) ]
     args += rebase_path(invoker.sources, root_build_dir)
   }