This enables HTTP/2 by default (for https only) if the user didn't
configure anything in their NPN/ALPN map. If they're using SPDY or an
alternate http2 or a newer http2 from x/net/http2, we do nothing
and don't use the standard library's vendored copy of x/net/http2.

Upstream remains golang.org/x/net/http2.

Update #6891

Change-Id: I69a8957a021a00ac353f9d7fdb9a40a5b69f2199
Reviewed-on: https://go-review.googlesource.com/15828
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This is the start of wiring up the HTTP/2 Transport. It is still
disabled in this commit.

This change does two main things:

1) Transport.RegisterProtocol now permits registering "http" or
   "https" (they previously paniced), and the semantics of the
   registered RoundTripper have been extended to say that the new
   sentinel error value (ErrSkipAltProtocol, added in this CL) means
   that the Transport's RoundTrip method proceeds as if the alternate
   protocol had not been registered. This gives us a place to register
   an alternate "https" RoundTripper which gets first dibs on using
   HTTP/2 if there's already a cached connection.

2) adds Transport.TLSNextProto, a map keyed by TLS NPN/ALPN protocol
   strings, similar in feel to the existing Server.TLSNextProto map.
   This map is the glue between the HTTP/1 and HTTP/2 clients, since
   we don't know which protocol we're going to speak (and thus which
   Transport type to use) until we've already made the TCP connection.

Updates #6891

Change-Id: I7328c7ff24f52d9fe4899facabf7ecc5dcb989f3
Reviewed-on: https://go-review.googlesource.com/16090
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This adds the http2 Transport method needed by
https://golang.org/cl/16090 to glue the HTTP/1 Transport
(net/http.Transport) to the http2.Transport without throwing away
fresh TCP connections after the TLS handshake determines which
NPN/ALPN protocol was selected.

Updates golang/go#6891

Change-Id: Iba004c8b1a149a5ee6c755d9a3fc1b19856a4e47
Reviewed-on: https://go-review.googlesource.com/16180
Reviewed-by: Andrew Gerrand <adg@golang.org>

We decided to glue together the HTTP/1 and HTTP/2 Transports in the
other direction, having the HTTP/1 code (net/http.Transport) start the
flow.

Remove the http2 Transport.Fallback for now, rather than leaving it
half implemented.

For background, see https://golang.org/cl/16090

Updates golang/go#6891

Change-Id: I511bc6d35a1a9a8e20010bd95ff694a894f42aa4
Reviewed-on: https://go-review.googlesource.com/16181
Reviewed-by: Andrew Gerrand <adg@golang.org>

Some polish and testing remains, but this should be the bulk of the
Transport work that was remaining.

There's one notable (but easy) TODO about sending WINDOW_UPDATE frames
every few hundred MB or so, but this is a checkpoint.

Updates golang/go#6891

Change-Id: Iced9850804bf2c069c75118895ee7c3750ba31b5
Reviewed-on: https://go-review.googlesource.com/16310
Reviewed-by: Blake Mizerany <blake.mizerany@gmail.com>

…ew dials

For integration with the net/http.Transport.

Updates golang/go#6891

Change-Id: I7a44e4c4259aa57cec1b54666c333b5fc519caf8
Reviewed-on: https://go-review.googlesource.com/16692
Reviewed-by: Blake Mizerany <blake.mizerany@gmail.com>

The GODEBUG option remains, for now, but only for turning it off.
We'll decide what to do with it before release.

This CL includes the dependent http2 change (https://golang.org/cl/16692)
in the http2 bundle (h2_bundle.go).

Updates #6891

Change-Id: If9723ef627c7ba4f7343dc8cb89ca88ef0fbcb10
Reviewed-on: https://go-review.googlesource.com/16693
Reviewed-by: Blake Mizerany <blake.mizerany@gmail.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This CL adds skipped failing tests, showing differences between HTTP/1
and HTTP/2 behavior. They'll be fixed in later commits.

Only a tiny fraction of the net/http tests have been split into their
"_h1" and "_h2" variants. That will also continue. (help welcome)

Updates #6891
Updates #13315
Updates #13316
Updates #13317

Change-Id: I16c3c381dbe267a3098fb266ab0d804c36473a64
Reviewed-on: https://go-review.googlesource.com/17046
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes found in the process of adding more A/B tests to net/http,
comparing HTTP/1 and HTTP/2 behaviors.

Most of the new tests are in Gerrit change Id9c45fad44cdf70ac9
in the "go" repo.

Fixes golang/go#13315
Fixes golang/go#13316
Fixes golang/go#13317
Fixes other stuff found in the process too
Updates golang/go#6891 (http2 support in general)

Change-Id: I83b5bfb471047312c0dcb0a0b21d709008f34136
Reviewed-on: https://go-review.googlesource.com/17204
Reviewed-by: Andrew Gerrand <adg@golang.org>

This compares the behavior of server handlers and the net/http
Transport in both HTTP/1 and HTTP/2 mode and verifies they're the
same.

This also moves some client<->server tests into clientserver_test.go.
Many of them were in serve_test.go or transport_test.go but were
basically testing both.

h2_bundle.go is an update of the golang.org/x/net/http2 code
from https://golang.org/cl/17204 (x/net git rev c745c36eab10)

Fixes #13315
Fixes #13316
Fixes #13317
Fixes other stuff found in the process too
Updates #6891 (http2 support in general)

Change-Id: Id9c45fad44cdf70ac95d2b89e578d66e882d3cc2
Reviewed-on: https://go-review.googlesource.com/17205
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

And updates h2_bundle.go with the fix from x/net/http2.

Fixes #13298
Updates #6891

Change-Id: Ia25f22fa10e2a64b9d59211269882681aa18c101
Reviewed-on: https://go-review.googlesource.com/17241
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

Fixes golang/go#13397
Updates golang/go#6891

Change-Id: I1e4c7bfe60c6abf9a03f2888aa6abc3891c309e7
Reviewed-on: https://go-review.googlesource.com/17134
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This mirrors the same behavior and API from the server code to the
client side: if TLSNextProto is nil, HTTP/2 is on by default for
both. If it's non-nil, the user was trying to do something fancy and
step out of their way.

Updates #6891

Change-Id: Ia31808b71f336a8d5b44b985591d72113429e1d4
Reviewed-on: https://go-review.googlesource.com/17300
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>