jni_helpers: Optimize IsNull()

webrtc/api/java/jni/jni_helpers.h

 /*
  *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 54 matching lines @@
 jobject GetObjectField(JNIEnv* jni, jobject object, jfieldID id);
 
 jstring GetStringField(JNIEnv* jni, jobject object, jfieldID id);
 
 jlong GetLongField(JNIEnv* jni, jobject object, jfieldID id);
 
 jint GetIntField(JNIEnv* jni, jobject object, jfieldID id);
 
 bool GetBooleanField(JNIEnv* jni, jobject object, jfieldID id);
 
-// Java references to "null" can only be distinguished as such in C++ by
-// creating a local reference, so this helper wraps that logic.
+// Returns true if |obj| == null in Java.
 bool IsNull(JNIEnv* jni, jobject obj);
 
 // Given a UTF-8 encoded |native| string return a new (UTF-16) jstring.
 jstring JavaStringFromStdString(JNIEnv* jni, const std::string& native);
 
 // Given a (UTF-16) jstring return a new UTF-8 native string.
 std::string JavaToStdString(JNIEnv* jni, const jstring& j_string);
 
 // Return the (singleton) Java Enum object corresponding to |index|;
 jobject JavaEnumFromIndex(JNIEnv* jni, jclass state_class,
@@ skipping 32 matching lines @@
   T operator*() const {
     return obj_;
   }
  private:
   T obj_;
 };
 
 }  // namespace webrtc_jni
 
 #endif  // WEBRTC_API_JAVA_JNI_JNI_HELPERS_H_