jar_file_jni_generator accepts jar_input_file optionally

build/jar_file_jni_generator.gypi

 # 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.
 
 # This file is meant to be included into a target to provide a rule
 # to generate jni bindings for system Java-files in a consistent manner.
 #
 # To use this, create a gyp target with the following form:
 # {
 #   'target_name': 'android_jar_jni_headers',
 #   'type': 'none',
 #   'variables': {
 #     'jni_gen_package': 'chrome',
 #     'input_java_class': 'java/io/InputStream.class',
 #   },
 #   'includes': [ '../build/jar_file_jni_generator.gypi' ],
 # },
+#
+# Optional variables:
+#  input_jar_file - The input jar file, if omitted, android_sdk_jar will be used.
 
 {
   'variables': {
     'jni_generator': '<(DEPTH)/base/android/jni_generator/jni_generator.py',
   },
   'actions': [
     {
       'action_name': 'generate_jni_headers_from_jar_file',
       'inputs': [
         '<(jni_generator)',
+        '<(input_jar_file)',
         '<(android_sdk_jar)',
       ],
       'variables': {
-        'java_class_name': '<!(basename <(input_java_class)|sed "s/\.class//")'
+        'java_class_name': '<!(basename <(input_java_class)|sed "s/\.class//")',
+        'input_jar_file%': '<(android_sdk_jar)'
       },
       'outputs': [
         '<(SHARED_INTERMEDIATE_DIR)/<(jni_gen_package)/jni/<(java_class_name)_jni.h',
       ],
       'action': [
         '<(jni_generator)',
         '-j',
-        '<(android_sdk_jar)',
+        '<(input_jar_file)',
         '--input_file',
         '<(input_java_class)',
         '--output_dir',
         '<(SHARED_INTERMEDIATE_DIR)/<(jni_gen_package)/jni',
         '--optimize_generation',
         '<(optimize_jni_generation)',
       ],
-      'message': 'Generating JNI bindings from  <(android_sdk_jar)/<(input_java_class)',
+      'message': 'Generating JNI bindings from  <(input_jar_file)/<(input_java_class)',
       'process_outputs_as_sources': 1,
     },
   ],
   # This target exports a hard dependency because it generates header
   # files.
   'hard_dependency': 1,
 }