Adding Java binding for CreateSender.

talk/app/webrtc/java/jni/peerconnection_jni.cc

Index: talk/app/webrtc/java/jni/peerconnection_jni.cc
diff --git a/talk/app/webrtc/java/jni/peerconnection_jni.cc b/talk/app/webrtc/java/jni/peerconnection_jni.cc
index 194f9ff98c1b2887b4ae16c921ab35a7088954ec..f04ee6c1b2b7c26609dcdc5ba7b7b920c38a930a 100644
--- a/talk/app/webrtc/java/jni/peerconnection_jni.cc
+++ b/talk/app/webrtc/java/jni/peerconnection_jni.cc
@@ -1753,6 +1753,27 @@ JOW(void, PeerConnection_nativeRemoveLocalStream)(
       reinterpret_cast<MediaStreamInterface*>(native_stream));
 }
 
+JOW(jobject, PeerConnection_nativeCreateSender)(
+    JNIEnv* jni, jobject j_pc, jstring j_kind) {
+  jclass j_rtp_sender_class = FindClass(jni, "org/webrtc/RtpSender");
+  jmethodID j_rtp_sender_ctor =
+      GetMethodID(jni, j_rtp_sender_class, "<init>", "(J)V");
+
+  std::string kind = JavaToStdString(jni, j_kind);
+  rtc::scoped_refptr<RtpSenderInterface> sender =
+      ExtractNativePC(jni, j_pc)->CreateSender(kind);
+  if (!sender.get()) {
+    return nullptr;
+  }
+  jlong nativeSenderPtr = jlongFromPointer(sender.get());
+  jobject j_sender =
+      jni->NewObject(j_rtp_sender_class, j_rtp_sender_ctor, nativeSenderPtr);
+  CHECK_EXCEPTION(jni) << "error during NewObject";
+  // Sender is now owned by Java object, and will be freed from there.

[AlexG, 2015/12/02 00:50:16]

nit: extend comment to list what method will free senders - I guess
peerconnection.dispose() and getSenders() ?

+  sender->AddRef();
+  return j_sender;
+}
+
 JOW(jobject, PeerConnection_nativeGetSenders)(JNIEnv* jni, jobject j_pc) {
   jclass j_array_list_class = FindClass(jni, "java/util/ArrayList");
   jmethodID j_array_list_ctor =