ART: Move RegisterNatives helper

Move the helper closer to the users.

Test: m test-art-host
Change-Id: Id05ce5f60af54d0c5aef0c7d8932706c4602fc94
diff --git a/runtime/native/native_util.h b/runtime/native/native_util.h
new file mode 100644
index 0000000..98384e0
--- /dev/null
+++ b/runtime/native/native_util.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_NATIVE_NATIVE_UTIL_H_
+#define ART_RUNTIME_NATIVE_NATIVE_UTIL_H_
+
+#include <jni.h>
+
+#include "android-base/logging.h"
+#include "base/macros.h"
+#include "ScopedLocalRef.h"
+
+namespace art {
+
+ALWAYS_INLINE inline void RegisterNativeMethodsInternal(JNIEnv* env,
+                                                        const char* jni_class_name,
+                                                        const JNINativeMethod* methods,
+                                                        jint method_count) {
+  ScopedLocalRef<jclass> c(env, env->FindClass(jni_class_name));
+  if (c.get() == nullptr) {
+    LOG(FATAL) << "Couldn't find class: " << jni_class_name;
+  }
+  jint jni_result = env->RegisterNatives(c.get(), methods, method_count);
+  CHECK_EQ(JNI_OK, jni_result);
+}
+
+#define REGISTER_NATIVE_METHODS(jni_class_name) \
+  RegisterNativeMethodsInternal(env, (jni_class_name), gMethods, arraysize(gMethods))
+
+}  // namespace art
+
+#endif  // ART_RUNTIME_NATIVE_NATIVE_UTIL_H_