Reland Use CopyOnWriteBuffer instead of Buffer to avoid unnecessary copies.

webrtc/api/java/jni/peerconnection_jni.cc

Index: webrtc/api/java/jni/peerconnection_jni.cc
diff --git a/webrtc/api/java/jni/peerconnection_jni.cc b/webrtc/api/java/jni/peerconnection_jni.cc
index d614ed6c29d12276baa2df3dded8efc0d50f6c1a..6c8192d8c669b73461b019364ca26dabb9a81de2 100644
--- a/webrtc/api/java/jni/peerconnection_jni.cc
+++ b/webrtc/api/java/jni/peerconnection_jni.cc
@@ -893,7 +893,7 @@ JOW(jboolean, DataChannel_sendNative)(JNIEnv* jni, jobject j_dc,
                                       jbyteArray data, jboolean binary) {
   jbyte* bytes = jni->GetByteArrayElements(data, NULL);
   bool ret = ExtractNativeDC(jni, j_dc)->Send(DataBuffer(
-      rtc::Buffer(bytes, jni->GetArrayLength(data)),
+      rtc::CopyOnWriteBuffer(bytes, jni->GetArrayLength(data)),
       binary));
   jni->ReleaseByteArrayElements(data, bytes, JNI_ABORT);
   return ret;