Revert of Rename RTPVideoHeader.isFirstPacket to .is_first_packet_in_frame.

webrtc/modules/video_coding/nack_module_unittest.cc

Index: webrtc/modules/video_coding/nack_module_unittest.cc
diff --git a/webrtc/modules/video_coding/nack_module_unittest.cc b/webrtc/modules/video_coding/nack_module_unittest.cc
index bb581fe002376390931d3372d2bde112e2c2eb34..fb7d0955de46ee00a10574956e23eeeec29d72cd 100644
--- a/webrtc/modules/video_coding/nack_module_unittest.cc
+++ b/webrtc/modules/video_coding/nack_module_unittest.cc
@@ -72,7 +72,7 @@
 
   sent_nacks_.clear();
   packet.frameType = kVideoFrameKey;
-  packet.is_first_packet_in_frame = true;
+  packet.isFirstPacket = true;
   packet.seqNum = 2;
   nack_module_.OnReceivedPacket(packet);
   EXPECT_EQ(0u, sent_nacks_.size());
@@ -239,11 +239,11 @@
   packet.seqNum = 0;
   nack_module_.OnReceivedPacket(packet);
   packet.seqNum = 1;
-  packet.is_first_packet_in_frame = true;
+  packet.isFirstPacket = true;
   packet.frameType = kVideoFrameKey;
   nack_module_.OnReceivedPacket(packet);
   packet.seqNum = 1001;
-  packet.is_first_packet_in_frame = false;
+  packet.isFirstPacket = false;
   packet.frameType = kVideoFrameKey;
   nack_module_.OnReceivedPacket(packet);
   EXPECT_EQ(999u, sent_nacks_.size());