Adding comments explaining Java createSender and setTrack methods.

webrtc/sdk/android/api/org/webrtc/RtpSender.java

Index: webrtc/sdk/android/api/org/webrtc/RtpSender.java
diff --git a/webrtc/sdk/android/api/org/webrtc/RtpSender.java b/webrtc/sdk/android/api/org/webrtc/RtpSender.java
index 358b87dff81fc4ec2388e9838bd30fa369063ddd..29779532d4de04eb2f5c52ca62219420c14c0b78 100644
--- a/webrtc/sdk/android/api/org/webrtc/RtpSender.java
+++ b/webrtc/sdk/android/api/org/webrtc/RtpSender.java
@@ -29,11 +29,20 @@ public class RtpSender {
     dtmfSender = (nativeDtmfSender != 0) ? new DtmfSender(nativeDtmfSender) : null;
   }
 
-  // If |takeOwnership| is true, the RtpSender takes ownership of the track
-  // from the caller, and will auto-dispose of it when no longer needed.
-  // |takeOwnership| should only be used if the caller owns the track; it is
-  // not appropriate when the track is owned by, for example, another RtpSender
-  // or a MediaStream.
+  /**
+   * Starts sending a new track, without requiring additional SDP negotiation.
+   * <p>
+   * Note: This is equivalent to replaceTrack in the official WebRTC API. It
+   * was just implemented before the standards group settled on a name.
+   *
+   * @param takeOwnership If true, the RtpSender takes ownership of the track
+   *                      from the caller, and will auto-dispose of it when no
+   *                      longer needed. |takeOwnership| should only be used if
+   *                      the caller owns the track; it is not appropriate when
+   *                      the track is owned by, for example, another RtpSender
+   *                      or a MediaStream.
+   * @return              true on success and false on failure.
+   */
   public boolean setTrack(MediaStreamTrack track, boolean takeOwnership) {
     if (!nativeSetTrack(nativeRtpSender, (track == null) ? 0 : track.nativeTrack)) {
       return false;