Remove old profile avatar assets

Remove old profile avatar assets

- see comment in theme_resources.grd
- this should have no practical effect except to flip the icons in the
windows profile shortcut .ico generation code (which up till now were
mirrored relative to the same icons in the new avatar menu, for historical
reasons).

Also move a mac-only dropshadow asset into mac dir.

BUG=522168
Committed: https://crrev.com/d8c33d01b4c88daf2e282c1341772aa7e9c49c37
Cr-Commit-Position: refs/heads/master@{#344376}

[Evan Stade, 2015-08-19 22:04:13]

estade@chromium.org changed reviewers:
+ oshima@chromium.org

[Evan Stade, 2015-08-19 22:04:28]

The CQ bit was checked by estade@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-19 22:04:47]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1285183012/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1285183012/1

[oshima, 2015-08-19 22:44:02]

lgtm

[Evan Stade, 2015-08-19 23:40:28]

The CQ bit was unchecked by estade@chromium.org

[Evan Stade, 2015-08-19 23:40:29]

The CQ bit was checked by estade@chromium.org

[Evan Stade, 2015-08-19 23:47:04]

The CQ bit was unchecked by estade@chromium.org

[Evan Stade, 2015-08-19 23:47:04]

The CQ bit was checked by estade@chromium.org

[Evan Stade, 2015-08-19 23:47:18]

The CQ bit was unchecked by estade@chromium.org

[Evan Stade, 2015-08-19 23:47:22]

The CQ bit was checked by estade@chromium.org

[commit-bot: I haz the power, 2015-08-20 00:01:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1285183012/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1285183012/1

[commit-bot: I haz the power, 2015-08-20 00:13:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-20 00:14:13]

Patchset 1 (id:??) landed as
https://crrev.com/d8c33d01b4c88daf2e282c1341772aa7e9c49c37
Cr-Commit-Position: refs/heads/master@{#344376}