Fix forward-declaration of RegistrationMethod in jni_registrar.h

base/android/jni_registrar.h

 // 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.
 
 #ifndef BASE_ANDROID_JNI_REGISTRAR_H_
 #define BASE_ANDROID_JNI_REGISTRAR_H_
 
 #include <jni.h>
 #include "base/basictypes.h"
 
 namespace base {
 namespace android {
 
-class RegistrationMethod;
+struct RegistrationMethod;
 
 // Registers the JNI bindings for the specified |method| definition containing
 // |count| elements.  Returns whether the registration of the given methods
 // succeeded.
 bool RegisterNativeMethods(JNIEnv* env,
                            const RegistrationMethod* method,
                            size_t count);
 
 }  // namespace android
 }  // namespace base
 
 #endif  // BASE_ANDROID_JNI_REGISTRAR_H_