Fixes for re-enabling more MSVC level 4 warnings: net/spdy/ edition

net/spdy/buffered_spdy_framer_unittest.cc

Index: net/spdy/buffered_spdy_framer_unittest.cc
diff --git a/net/spdy/buffered_spdy_framer_unittest.cc b/net/spdy/buffered_spdy_framer_unittest.cc
index ef5576ae8cd5443aeb307c6a7ab057fc36ef3f81..a96bad5b159c4582b652f242aba933bfb5c8819c 100644
--- a/net/spdy/buffered_spdy_framer_unittest.cc
+++ b/net/spdy/buffered_spdy_framer_unittest.cc
@@ -21,8 +21,8 @@ class TestBufferedSpdyVisitor : public BufferedSpdyFramerVisitorInterface {
         syn_reply_frame_count_(0),
         headers_frame_count_(0),
         push_promise_frame_count_(0),
-        header_stream_id_(-1),
-        promised_stream_id_(-1) {
+        header_stream_id_(static_cast<SpdyStreamId>(-1)),
+        promised_stream_id_(static_cast<SpdyStreamId>(-1)) {
   }
 
   virtual void OnError(SpdyFramer::SpdyError error_code) OVERRIDE {