android: Hide JNI exports by default.

tools/android/memconsumer/memconsumer.gyp

 # Copyright 2013 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.
 
 {
   'targets': [
     {
       'target_name': 'memconsumer',
       'type': 'none',
       'dependencies': [
@@ skipping 10 matching lines @@
         'native_lib_target': 'libmemconsumer',
       },
       'dependencies': [
         'libmemconsumer',
       ],
       'includes': [ '../../../build/java_apk.gypi' ],
     },
     {
       'target_name': 'libmemconsumer',
       'type': 'shared_library',
+      'variables': {
+        # This library uses native JNI exports; tell gyp so that the required
+        # symbols will be kept.
+        'use_native_jni_exports': 1,
+      },
       'sources': [
         'memconsumer_hook.cc',
       ],
       'libraries': [
         '-llog',
       ],
     },
   ],
 }