GitLab

Add proper constness.

Change ReadIconCallback signature to return `const SkBitmap&`.

These changes are required for the integration with AppService.

This code is disabled by default behind kDesktopPWAsWithoutExtensions
base feature.

Bug: 1029221
Change-Id: I4ec06716014686c607ea86da864efe017b0ad585
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1941458
Auto-Submit: Alexey Baskakov <loyso@chromium.org>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719903}