Simplify frame type handling in SpdyStream method.

In SpdyStream::OnFrameWriteComplete(), remove early returns for
specific, allowed frame types, remove CHECK on frame type, and replace
them with an early return for any frame type other than HEADERS and
DATA.  The CHECK was not particularily useful, since it is okay not to
take action when a frame write is complete, but with the CHECK in place
one is forced to modify this method when adding a new frame type (that
is why the reserved frame type logic got in there at
https://crrev.com/c/1207750).  This change makes the code easier to
extend with potential future frame types like PRIORITY_UPDATE.

Removing hardcoded reserved frame types formula is also beneficial,
because special treatment of reserved frame types is potentially
error-prone, and also goes against the spirit of GREASE.

Change-Id: I53efa954411db42af051b4a06c7c3b30b969b0b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2615479Reviewed-by: David Schinazi <dschinazi@chromium.org>
Commit-Queue: Bence Béky <bnc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843002}

net/spdy/spdy_stream.cc

@@ -600,21 +600,12 @@ void SpdyStream::OnPaddingConsumed(size_t len) {
 
 void SpdyStream::OnFrameWriteComplete(spdy::SpdyFrameType frame_type,
                                       size_t frame_size) {
-  // PRIORITY writes are allowed at any time and do not trigger a state update.
-  if (frame_type == spdy::SpdyFrameType::PRIORITY) {
+  if (frame_type != spdy::SpdyFrameType::HEADERS &&
+      frame_type != spdy::SpdyFrameType::DATA) {
     return;
   }
 
-  // Frame types reserved in
-  // https://tools.ietf.org/html/draft-bishop-httpbis-grease-00 ought to be
-  // ignored.
-  if (static_cast<uint8_t>(frame_type) % 0x1f == 0x0b)
-    return;
-
   DCHECK_NE(type_, SPDY_PUSH_STREAM);
-  CHECK(frame_type == spdy::SpdyFrameType::HEADERS ||
-        frame_type == spdy::SpdyFrameType::DATA)
-      << frame_type;
 
   int result = (frame_type == spdy::SpdyFrameType::HEADERS)
                    ? OnHeadersSent()