commit 0589408e6eb8c755cbbc249c89685cdac8ffa36b
author Tsuyoshi Horo <horo@chromium.org> Fri Mar 28 01:26:28 2025
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Mar 28 01:26:28 2025
tree f316c4767eb3902293f0a0e76cd66d69f96e77f6
parent f5f18d7bc403c34e4a41847901ffc84fddb59096

RendererSideContentDecoding: Ensure network service decodes SXGs

Signed Exchanges (SXG) must be parsed within the browser process. This
requires the network service to always decode the SXG first, handling
any `Content-Encoding` (like gzip) specified in the response headers
before forwarding the data.

The `URLRequest::client_side_content_decoding_enabled` flag allows
clients (like renderer process) to perform decoding themselves,
typically meaning the network service should skip decoding. This created
a conflict for SXG, where the network service might incorrectly skip
decoding if the flag was enabled.

This CL resolves the conflict by modifying the stream setup logic in
`URLRequestHttpJob::SetUpSourceStream`:
1. It now checks the `Content-Type` of the response.
2. If the type is `application/signed-exchange`, network-level decoding
   (via `FilterSourceStream`) is applied regardless of the
   `client_side_content_decoding_enabled` flag.
3. For all other content types, the
   `client_side_content_decoding_enabled` flag continues to determine
   whether the network service decodes or passes the encoded stream to
   the client.

To correctly inform clients about *which* encodings (if any) they need
to handle, this CL also introduces
`URLRequest::GetClientSideContentDecodingTypes`. This method reports the
list of encodings that were *actually* skipped by the network service
(i.e., only for non-SXG responses when the flag was enabled).
`URLLoader` is updated to use this method to populate
`URLResponseHead::client_side_content_decoding_types`.

A browser test (`SignedExchangeRequestHandlerBrowserTest.Compressed`)
is added using a compressed SXG (`.sxg.gz`) to ensure the network
service correctly decodes SXG payloads served with `Content-Encoding`.

Bug: 406313013, 391950057
Change-Id: Ic6efb534c540e6075ebe76b42b369a294f34ab76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6399234
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1439153}