cast return values in uint16_t RTPFile::Read() to uint16_t to avoid compile error
BUG=3663
TESTED=ninja local build on windows.
R=andrew@webrtc.org, kwiberg@webrtc.org, thorcarpenter@google.com

Review URL: https://webrtc-codereview.appspot.com/16229004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@7049 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/modules/audio_coding/main/test/RTPFile.cc b/modules/audio_coding/main/test/RTPFile.cc
index b886bde..5c04465 100644
--- a/modules/audio_coding/main/test/RTPFile.cc
+++ b/modules/audio_coding/main/test/RTPFile.cc
@@ -231,13 +231,13 @@
   EXPECT_EQ(lengthBytes, plen + 8);
 
   if (plen == 0) {
-    return 0;
+    return static_cast<uint16_t>(0);
   }
   if (payloadSize < (lengthBytes - 20)) {
-    return 0;
+    return static_cast<uint16_t>(0);
   }
   if (lengthBytes < 20) {
-    return 0;
+    return static_cast<uint16_t>(0);
   }
   lengthBytes -= 20;
   EXPECT_EQ(lengthBytes, fread(payloadData, 1, lengthBytes, _rtpFile));