Add templates for building java and running the jni_generator.

build/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 Java-files in a consistent manner.
+#
+# To use this, create a gyp target with the following form:
+# {
+#   'target_name': 'base_jni_headers',
+#   'type': 'none',
+#   'variables': {
+#       'java_sources': [
+#         'android/java/org/chromium/base/BuildInfo.java',
+#         'android/java/org/chromium/base/PathUtils.java',
+#         'android/java/org/chromium/base/SystemMessageHandler.java',
+#       ],
+#       'jni_headers': [
+#         '<(SHARED_INTERMEDIATE_DIR)/base/jni/build_info_jni.h',
+#         '<(SHARED_INTERMEDIATE_DIR)/base/jni/path_utils_jni.h',
+#         '<(SHARED_INTERMEDIATE_DIR)/base/jni/system_message_handler_jni.h',
+#       ],
+#   },
+#   'includes': [ '../build/jni_generator.gypi' ],
+# }
+#
+# The ordering of the java_sources must match the ordering of jni_headers. The
+# result is that for each Java file listed in java_sources, the corresponding
+# entry in jni_headers contains the JNI bindings produced from running the
+# jni_generator on the input file.
+#
+# See base/android/jni_generator/jni_generator.py for more info about the
+# format of generating JNI bindings.
+
+{
+  'actions': [
+      {
+        'action_name': 'generate_jni_headers',
+        'type': 'none',
+        'inputs': [
+          '<(DEPTH)/base/android/jni_generator/jni_generator.py',
+          '<@(java_sources)',
+        ],
+        'outputs': [
+          '<@(jni_headers)',
+        ],
+        'action': [
+          'python',
+          '<(DEPTH)/base/android/jni_generator/jni_generator.py',
+          '-o',
+          '<@(_inputs)',
+          '<@(_outputs)',
+        ],
+      },
+  ],
+}