chore: cherry-pick 1d491fff578b, f7b87bea19d7 and 549d92d7ef35 from chromium

[ppontes]

[Merge M112] Remove the second WeakPtrFactory from SpdyProxyClientSocket

It was introduced [1] to work around an old issue that wouldn't happen
any more since we store a write callback in the class. Instead of having
the second WeakPtrFactory and moving the callback, we can just keep it
until RunWriteCallback() is called.

This is a speculative fix for the linked bug.

[1] https://codereview.chromium.org/338583003/

(cherry picked from commit 01b25615896b911e21103dd381fafc1f85886d91)

Bug: 1428820
Change-Id: I0b5af2675b68188e208c2ecd42293251b2722b28
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4393905
Reviewed-by: Adam Rice ricea@chromium.org
Commit-Queue: Kenichi Ishibashi bashi@chromium.org
Cr-Original-Commit-Position: refs/heads/main@{#1125216}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4410320
Auto-Submit: Kenichi Ishibashi bashi@chromium.org
Bot-Commit: Rubber Stamper rubber-stamper@appspot.gserviceaccount.com
Commit-Queue: Rubber Stamper rubber-stamper@appspot.gserviceaccount.com
Cr-Commit-Position: refs/branch-heads/5615@{#1171}
Cr-Branched-From: 9c6408ef696e83a9936b82bbead3d41c93c82ee4-refs/heads/main@{#1109224}

============

[Merge M112] Check SpdyProxyClientSocket is alive after write callback

To ensure that we don't use any member field.

(cherry picked from commit b71541b22ca19d5c3a7c01fedffe521b26577b72)

Bug: 1428820
Change-Id: Icf6677c652a47dc2fd2d01675e94cda031a015f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4394863
Reviewed-by: Adam Rice ricea@chromium.org
Commit-Queue: Kenichi Ishibashi bashi@chromium.org
Cr-Original-Commit-Position: refs/heads/main@{#1125634}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4410322
Commit-Queue: Rubber Stamper rubber-stamper@appspot.gserviceaccount.com
Auto-Submit: Kenichi Ishibashi bashi@chromium.org
Bot-Commit: Rubber Stamper rubber-stamper@appspot.gserviceaccount.com
Cr-Commit-Position: refs/branch-heads/5615@{#1172}
Cr-Branched-From: 9c6408ef696e83a9936b82bbead3d41c93c82ee4-refs/heads/main@{#1109224}

============

Check callback availability in SpdyProxyClientSocket::RunWriteCallback

OnClose() could consume write_callback_ so it may not be available
when RunWriteCallback() is invoked.

Bug: 1428820
Change-Id: I9a5ade62d67f5bf15e12d0915d1ad6098657ffd4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4437791
Code-Coverage: Findit findit-for-me@appspot.gserviceaccount.com
Reviewed-by: Adam Rice ricea@chromium.org
Commit-Queue: Kenichi Ishibashi bashi@chromium.org
Cr-Commit-Position: refs/heads/main@{#1131689}

Notes: Security: backported fix for 1428820.

[release-clerk]

Release Notes Persisted

Security: backported fix for 1428820.