Reland "Make use of new hex decoding function for extensions color string parser."

This reverts commit 11ec6a9b286b6ff4b3bc2ace3e99268959692b57.

Reason for revert: The failed screenshot tests were not caused by this change

Original change's description:
> Revert "Make use of new hex decoding function for extensions color string parser."
> 
> This reverts commit 2de0ccb8734895523e3ee3051f6ccb8bf6f9687c.
> 
> Reason for revert: Suspecting cause for screenshot test failure. Seems unlikely but this is the only color related CL in regression range. crbug.com/1023255
> 
> Original change's description:
> > Make use of new hex decoding function for extensions color string parser.
> > 
> > Bug: 1021236
> > Change-Id: I1d1b5180048eb36fa78406a02fc3277cba0dcf63
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1904809
> > Commit-Queue: Eric Roman <[email protected]>
> > Commit-Queue: Reilly Grant <[email protected]>
> > Auto-Submit: Eric Roman <[email protected]>
> > Reviewed-by: Reilly Grant <[email protected]>
> > Cr-Commit-Position: refs/heads/master@{#713942}
> 
> [email protected],[email protected]
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 1021236
> Change-Id: I474f4e07583f571722e4bacf28ae482c071276a8
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1909669
> Reviewed-by: Keishi Hattori <[email protected]>
> Commit-Queue: Keishi Hattori <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#714159}

[email protected],[email protected],[email protected]

Change-Id: Ifff4b8df577ad13e2cbffcfe90044caac9b0a888
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1021236
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1909654
Reviewed-by: Eric Roman <[email protected]>
Commit-Queue: Eric Roman <[email protected]>
Auto-Submit: Eric Roman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#714282}
1 file changed