Revert of Refactor download image-MIME-type-detection code.

Revert of Refactor download image-MIME-type-detection code. (patchset #3 id:40001 of https://codereview.chromium.org/2219953004/ )

Reason for revert:
accidentally mixed in another change (https://codereview.chromium.org/2225543002/)

Original issue's description:
> Refactor download image-MIME-type-detection code.
>
> Refactor duplicated image-MIME-type-detection code from
> DownloadCommands and DownloadItemNotification into a new
> DownloadItemModel::HasSupportedImageMimeType() method.
>
> BUG=605805
>
> Committed: https://crrev.com/759969dbc064ab0925287ad8a62eacf588faec7f
> Cr-Commit-Position: refs/heads/master@{#410382}

TBR=rdsmith@chromium.org,svaldez@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=605805
Committed: https://crrev.com/f05766e8629713e1ad10dc81cdd56558b6ea0427
Cr-Commit-Position: refs/heads/master@{#410403}

[Daniel Erat, 2016-08-08 18:49:42]

The CQ bit was checked by derat@chromium.org

[Daniel Erat, 2016-08-08 18:49:42]

Created Revert of Refactor download image-MIME-type-detection code.

[commit-bot: I haz the power, 2016-08-08 18:50:03]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-08 18:50:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-08 18:52:52]

Description was changed from

==========
Revert of Refactor download image-MIME-type-detection code. (patchset #3
id:40001 of https://codereview.chromium.org/2219953004/ )

Reason for revert:
accidentally mixed in another change
(https://codereview.chromium.org/2225543002/)

Original issue's description:
> Refactor download image-MIME-type-detection code.
> 
> Refactor duplicated image-MIME-type-detection code from
> DownloadCommands and DownloadItemNotification into a new
> DownloadItemModel::HasSupportedImageMimeType() method.
> 
> BUG=605805
> 
> Committed: https://crrev.com/759969dbc064ab0925287ad8a62eacf588faec7f
> Cr-Commit-Position: refs/heads/master@{#410382}

TBR=rdsmith@chromium.org,svaldez@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=605805
==========

to

==========
Revert of Refactor download image-MIME-type-detection code. (patchset #3
id:40001 of https://codereview.chromium.org/2219953004/ )

Reason for revert:
accidentally mixed in another change
(https://codereview.chromium.org/2225543002/)

Original issue's description:
> Refactor download image-MIME-type-detection code.
>
> Refactor duplicated image-MIME-type-detection code from
> DownloadCommands and DownloadItemNotification into a new
> DownloadItemModel::HasSupportedImageMimeType() method.
>
> BUG=605805
>
> Committed: https://crrev.com/759969dbc064ab0925287ad8a62eacf588faec7f
> Cr-Commit-Position: refs/heads/master@{#410382}

TBR=rdsmith@chromium.org,svaldez@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=605805

Committed: https://crrev.com/f05766e8629713e1ad10dc81cdd56558b6ea0427
Cr-Commit-Position: refs/heads/master@{#410403}
==========

[commit-bot: I haz the power, 2016-08-08 18:52:53]

Patchset 1 (id:??) landed as
https://crrev.com/f05766e8629713e1ad10dc81cdd56558b6ea0427
Cr-Commit-Position: refs/heads/master@{#410403}