Revert of [Fallback icons] Change "explicit flow" interface so color hex strings don't use "#".

Revert of [Fallback icons] Change "explicit flow" interface so color hex strings don't use "#". (patchset #4 id:60001 of https://codereview.chromium.org/988863002/)

Reason for revert:
This seems to be causing FallbackIconUrlParserTest unit_tests to fail, see, for example,
https://build.chromium.org/p/chromium.memory/builders/Mac%20ASan%2064%20Tests%20%281%29/builds/7625
https://build.chromium.org/p/chromium.memory/builders/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/builds/7297
https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests%20%28dbg%29%281%29/builds/39924
https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests%20%28dbg%29%281%29%2832%29/builds/10797

Original issue's description:
> [Fallback icons] Change "explicit flow" interface so color hex strings don't use "#".
>
> Design: go/chrome-fallback-icons
>
> Fallback icon "explicit flow" URL used to have '#' in hex colors, e.g.:
>
> chrome://fallback-icon/,#01f,#123456,,/http://www.google.com
>
> Problem: "#" denotes fragment in URLs, so we get rid of it. This causes no ambiguity
> with named color (e.g., "red") because no named color consists of letters a-f only.
> Also adding "ARGB" hex color since this is supported in Skia color parsing.
>
> BUG=455063
>
> Committed: https://crrev.com/8fa91aabefbe9784eca0c169bc2ad2dd92f5d887
> Cr-Commit-Position: refs/heads/master@{#319630}

TBR=jhawkins@chromium.org,huangs@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=455063
Committed: https://crrev.com/8d63f0cd7fdd28dd64b9c25a0c4044bac88df5a5
Cr-Commit-Position: refs/heads/master@{#319677}

[Bence, 2015-03-09 17:45:37]

Created Revert of [Fallback icons] Change "explicit flow" interface so color hex
strings don't use "#".

[commit-bot: I haz the power, 2015-03-09 17:46:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/989133003/1

[commit-bot: I haz the power, 2015-03-09 17:48:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-09 17:49:37]

Patchset 1 (id:??) landed as
https://crrev.com/8d63f0cd7fdd28dd64b9c25a0c4044bac88df5a5
Cr-Commit-Position: refs/heads/master@{#319677}