Accept and ignore PRIORITY frames in SPDY4+.

net/spdy/spdy_protocol.cc

Index: net/spdy/spdy_protocol.cc
diff --git a/net/spdy/spdy_protocol.cc b/net/spdy/spdy_protocol.cc
index 3413cb21ced1d4c7372bdf225d745e999b5e2b39..94c8144a67643dbc749053f0d662b9aeb521ea54 100644
--- a/net/spdy/spdy_protocol.cc
+++ b/net/spdy/spdy_protocol.cc
@@ -98,7 +98,8 @@ SpdyFrameType SpdyConstants::ParseFrameType(SpdyMajorVersion version,
           return DATA;
         case 1:
           return HEADERS;
-        // TODO(hkhalil): Add PRIORITY.
+        case 2:
+          return PRIORITY;
         case 3:
           return RST_STREAM;
         case 4:
@@ -158,7 +159,8 @@ int SpdyConstants::SerializeFrameType(SpdyMajorVersion version,
           return 0;
         case HEADERS:
           return 1;
-        // TODO(hkhalil): Add PRIORITY.
+        case PRIORITY:
+          return 2;
         case RST_STREAM:
           return 3;
         case SETTINGS: