Android JNI gen: Don't emit code for empty RegisterNatives()

base/android/jni_generator/testNativeExportsOnlyOption.golden

Index: base/android/jni_generator/testNativeExportsOnlyOption.golden
diff --git a/base/android/jni_generator/testNativeExportsOnlyOption.golden b/base/android/jni_generator/testNativeExportsOnlyOption.golden
index 067e71076512a080956060c44db2987b238fc36d..2ca3d700c8630f28e5ff734ead429e5d46b7e78b 100644
--- a/base/android/jni_generator/testNativeExportsOnlyOption.golden
+++ b/base/android/jni_generator/testNativeExportsOnlyOption.golden
@@ -188,12 +188,4 @@ static_cast<jstring>(env->CallStaticObjectMethod(SampleForTests_clazz(env),
   return ScopedJavaLocalRef<jstring>(env, ret);
 }
 
-// Step 3: RegisterNatives.
-
-static bool RegisterNativesImpl(JNIEnv* env) __attribute__((unused));
-static bool RegisterNativesImpl(JNIEnv* env) {
-
-  return true;
-}
-
 #endif  // org_chromium_example_jni_generator_SampleForTests_JNI