Add option to print classpath to script.

This will be read by the test runner when sharding junit tests.

Bug: 1138506, 1141757
Change-Id: I050064f4b0c4ef766246b60469f59ee69a3893ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2506172Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: benjamin joyce <bjoyce@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822736}

build/android/gyp/create_java_binary_script.py

@@ -44,8 +44,15 @@ parser = argparse.ArgumentParser()
 parser.add_argument('--jar-args')
 parser.add_argument('--jvm-args')
 parser.add_argument('--classpath')
+# Test_runner parses the classpath for sharding junit tests.
+parser.add_argument('--print-classpath', action='store_true',
+                    help='Prints the classpass. Used by test_runner.')
 known_args, unknown_args = parser.parse_known_args(sys.argv[1:])
 
+if known_args.print_classpath:
+  sys.stdout.write(':'.join(classpath))
+  sys.exit(0)
+
 if known_args.jvm_args:
   jvm_arguments = known_args.jvm_args.strip('"').split()
   java_cmd.extend(jvm_arguments)
@@ -96,12 +103,11 @@ def main(argv):
 
   with build_utils.AtomicOutput(options.output) as script:
     script.write(
-        script_template.format(
-            classpath=('"%s"' % '", "'.join(classpath)),
-            java_path=repr(java_path),
-            main_class=options.main_class,
-            extra_program_args=repr(extra_program_args),
-            noverify_flag=noverify_flag))
+        script_template.format(classpath=('"%s"' % '", "'.join(classpath)),
+                               java_path=repr(java_path),
+                               main_class=options.main_class,
+                               extra_program_args=repr(extra_program_args),
+                               noverify_flag=noverify_flag))
 
   os.chmod(options.output, 0750)