Revert "Convert most of /chrome/browser to use ARC"

This reverts commit c46ae3d6.

Reason for revert: Bad include breaking Mac build:
https://ci.chromium.org/ui/p/chromium/builders/ci/Mac%20Builder/194360/overview

Original change's description:
> Convert most of /chrome/browser to use ARC
>
> See https://chromium.googlesource.com/chromium/src/+/main/docs/mac/arc.md
> for information about this conversion.
>
> This (plus more files) was previously committed as
> https://crrev.com/c/4546398 but reverted. This CL omits the ARCifying
> of complicated files, but ARCifies the files in /chrome/browser with
> straightforward, non-controversial changes.
>
> Bug: 1280317
> Change-Id: Ibb34c35f8baa7616f13638e1f7a1d2c67b419a6e
> Include-Ci-Only-Tests: true
> Cq-Include-Trybots: luci.chromium.try:ios-blink-dbg-fyi
> Cq-Include-Trybots: luci.chrome.try:mac-chrome
> Validate-Test-Flakiness: skip
> Low-Coverage-Reason: Doing core refactoring across all of Chromium; I do not own this code
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4566446


> Auto-Submit: Avi Drissman <avi@chromium.org>
> Reviewed-by: Leonard Grey <lgrey@chromium.org>
> Commit-Queue: Avi Drissman <avi@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1149425}

Bug: 1280317
Change-Id: Ifed40e8de39c0ecd72505e048d94d2395098face
Cq-Include-Trybots: luci.chromium.try:ios-blink-dbg-fyi
Cq-Include-Trybots: luci.chrome.try:mac-chrome
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4569563


Auto-Submit: Alan Cutter <alancutter@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1149433}