Adding Java and Obj-C bindings for RtpEncodingParameters.ssrc.

webrtc/sdk/objc/Framework/Classes/RTCRtpEncodingParameters.mm

Index: webrtc/sdk/objc/Framework/Classes/RTCRtpEncodingParameters.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCRtpEncodingParameters.mm b/webrtc/sdk/objc/Framework/Classes/RTCRtpEncodingParameters.mm
index af07a0485d64e92f57ddd00842264f0cb91e1b63..be47894a8fe18837bd3a67efaaa1966bbf1c9364 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCRtpEncodingParameters.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCRtpEncodingParameters.mm
@@ -14,6 +14,7 @@
 
 @synthesize isActive = _isActive;
 @synthesize maxBitrateBps = _maxBitrateBps;
+@synthesize ssrc = _ssrc;
 
 static const int kBitrateUnlimited = -1;
 
@@ -30,6 +31,9 @@ static const int kBitrateUnlimited = -1;
       _maxBitrateBps =
           [NSNumber numberWithInt:nativeParameters.max_bitrate_bps];
     }
+    if (nativeParameters.ssrc) {
+      _ssrc = [NSNumber numberWithUnsignedLong:*nativeParameters.ssrc];
+    }
   }
   return self;
 }
@@ -40,6 +44,9 @@ static const int kBitrateUnlimited = -1;
   if (_maxBitrateBps != nil) {
     parameters.max_bitrate_bps = _maxBitrateBps.intValue;
   }
+  if (_ssrc != nil) {
+    parameters.ssrc = rtc::Optional<uint32_t>(_ssrc.unsignedLongValue);
+  }
   return parameters;
 }