commit 1c6efa6f5cf677b997af14e68abc49d05d8073ca
author Tsuyoshi Horo <horo@chromium.org> Tue Feb 25 06:30:44 2025
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Feb 25 06:30:44 2025
tree fc8f1d4883246a22354f2d911b4c614b8201cfb4
parent 68c4e2a0f004ddbcc024b1f60bf60ccac6219c81

Refactor content encoding handling in URLRequestHttpJob

This CL refactors content encoding handling in `URLRequestHttpJob` and
introduces a new UMA, `Net.ContentEncodingType2`, for improved accuracy.

* Refactoring:

- Moves `Content-Encoding` header parsing and decoding `SourceStream`
  creation logic from `URLRequestHttpJob` to `FilterSourceStream`.
  - Adds `FilterSourceStream::GetContentEncodingTypes` to parse the
    `Content-Encoding` header.
  - Adds `FilterSourceStream::CreateDecodingSourceStream` to create
    a chain of decoding `SourceStream`s.
- Updates `URLRequestHttpJob` to use these new methods, simplifying its
  implementation.
- Adds unit tests for `FilterSourceStream::GetContentEncodingTypes`.

Motivation: These changes lay the groundwork for the Renderer-Side
Content Decoding project.


* UMA Changes:

Replaces the existing `Net.ContentEncodingType` UMA with
`Net.ContentEncodingType2` to address the following limitations:

- `Net.ContentEncodingType`:
  - A missing `Content-Encoding` header was incorrectly recorded as
    `Unknown`.
  - An empty `Content-Encoding` header, or one containing only
    `identity`, resulted in no UMA entry being recorded.
- `Net.ContentEncodingType2`:
  - Correctly records all cases where no decoding `SourceStream` is
    created (missing, empty, or `identity` header) as `None`.

OBSOLETE_HISTOGRAM[Net.ContentEncodingType]=Replaced by Net.ContentEncodingType2

Bug: 391950057
Change-Id: I4c37d4e8f056c57023e1d0f98f8463ef1694aaa1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6290949
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Nidhi Jaju <nidhijaju@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1424330}