Fix size_t truncations in net for 64-bit VS 2015

net/server/web_socket_encoder.cc

Index: net/server/web_socket_encoder.cc
diff --git a/net/server/web_socket_encoder.cc b/net/server/web_socket_encoder.cc
index 738f39dd145f5b87b71aae68bfacdb1b4114ca5b..6e3da4e30ac0965355f983dfd067ddca669619a1 100644
--- a/net/server/web_socket_encoder.cc
+++ b/net/server/web_socket_encoder.cc
@@ -149,9 +149,9 @@ void EncodeFrameHybi17(const std::string& message,
   int reserved1 = compressed ? kReserved1Bit : 0;
   frame.push_back(kFinalBit | op_code | reserved1);
   char mask_key_bit = masking_key != 0 ? kMaskBit : 0;
-  if (data_length <= kMaxSingleBytePayloadLength)
-    frame.push_back(data_length | mask_key_bit);
-  else if (data_length <= 0xFFFF) {
+  if (data_length <= kMaxSingleBytePayloadLength) {
+    frame.push_back(static_cast<char>(data_length) | mask_key_bit);
+  } else if (data_length <= 0xFFFF) {
     frame.push_back(kTwoBytePayloadLengthField | mask_key_bit);
     frame.push_back((data_length & 0xFF00) >> 8);
     frame.push_back(data_length & 0xFF);