Add Cast PLI support on sender side.

media/cast/net/mock_cast_transport_sender.h

Index: media/cast/net/mock_cast_transport_sender.h
diff --git a/media/cast/net/mock_cast_transport_sender.h b/media/cast/net/mock_cast_transport_sender.h
index bf1dfc0dc1ae7e11ec3aba05bdb9dca1a8c75066..ad3cdf59139cdf07b6420e36ec2d39050ba1228c 100644
--- a/media/cast/net/mock_cast_transport_sender.h
+++ b/media/cast/net/mock_cast_transport_sender.h
@@ -18,14 +18,16 @@ class MockCastTransportSender : public CastTransportSender {
   MockCastTransportSender();
   virtual ~MockCastTransportSender();
 
-  MOCK_METHOD3(InitializeAudio, void(
-      const CastTransportRtpConfig& config,
-      const RtcpCastMessageCallback& cast_message_cb,
-      const RtcpRttCallback& rtt_cb));
-  MOCK_METHOD3(InitializeVideo, void(
-      const CastTransportRtpConfig& config,
-      const RtcpCastMessageCallback& cast_message_cb,
-      const RtcpRttCallback& rtt_cb));
+  MOCK_METHOD4(InitializeAudio,
+               void(const CastTransportRtpConfig& config,
+                    const RtcpCastMessageCallback& cast_message_cb,
+                    const RtcpRttCallback& rtt_cb,
+                    const RtcpPliCallback& pli_cb));
+  MOCK_METHOD4(InitializeVideo,
+               void(const CastTransportRtpConfig& config,
+                    const RtcpCastMessageCallback& cast_message_cb,
+                    const RtcpRttCallback& rtt_cb,
+                    const RtcpPliCallback& pli_cb));
   MOCK_METHOD2(InsertFrame, void(uint32_t ssrc, const EncodedFrame& frame));
   MOCK_METHOD3(SendSenderReport,
                void(uint32_t ssrc,