Support for png images served with "image/x-png" mime type

Support for png images served with "image/x-png" mime type

The image/x-png is a non-standard mimetype, now replaced by image/png.
Adding support to be backward compatible and also match the behavior
of other browsers like Firefox.

BUG=25293
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=269105

[spartha, 2014-05-06 14:20:49]

The test case for the fix is available at
https://codereview.chromium.org/270473002/

[abarth-chromium, 2014-05-06 17:44:21]

lgtm

[commit-bot: I haz the power, 2014-05-06 17:44:54]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sudarshan.p@samsung.com/264043018/1

[commit-bot: I haz the power, 2014-05-07 02:52:46]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  chromium_presubmit on tryserver.chromium
  win_chromium_compile_dbg on tryserver.chromium
  win_chromium_rel on tryserver.chromium

[spartha, 2014-05-07 04:19:53]

The CQ bit was unchecked by sudarshan.p@samsung.com

[spartha, 2014-05-07 04:55:27]

Need a owner lgtm!

[Ryan Sleevi, 2014-05-07 18:55:53]

LGTM based on abarth.

[spartha, 2014-05-08 07:32:08]

The CQ bit was checked by sudarshan.p@samsung.com

[commit-bot: I haz the power, 2014-05-08 07:34:53]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sudarshan.p@samsung.com/264043018/1

[commit-bot: I haz the power, 2014-05-08 23:51:07]

Change committed as 269105