Use combined native/manual JNI registration.

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',
@@ skipping 55 matching lines @@
   'hard_dependency': 1,
   'conditions': [
     ['android_webview_build==1', {
       'variables': {
         'native_exports%': '--native_exports',
       },
       'dependencies': [
         '<(DEPTH)/build/android/android_exports.gyp:android_exports',
       ],
     }],
+    ['clang==0', {
+      # Clang builds currently fail with --native_exports_optional due to
+      # http://llvm.org/bugs/show_bug.cgi?id=22602 - only enable for gcc.
+      # http://crbug.com/442327
+      'variables': {
+        'native_exports%': '--native_exports_optional',
+      },
+    }],
   ],
 }