Revert r150228 "Add support for PNG representation in gfx::Image"

Revert r150228 "Add support for PNG representation in gfx::Image"

Currently all conversions to or from PNG will request (and so possibly
create and cache) an ImageSkia intermediate representation.

Depends on http://codereview.chromium.org/10799014/

I'm reverting because this has Uninitialized issue and a test is failing on mac valgrind bots

TBR=cjhopman@chromium.org
BUG=123865
TEST=none
NOTRY=true

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=150294

[commit-bot: I haz the power, 2012-08-07 05:47:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/oshima@chromium.org/10826181/1

[commit-bot: I haz the power, 2012-08-07 05:58:32]

Commit queue rejected this change because the description was changed
between the time the change entered the commit queue and the time it
was ready to commit. You can safely check the commit box again.

[commit-bot: I haz the power, 2012-08-07 07:03:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/oshima@chromium.org/10826181/1

[commit-bot: I haz the power, 2012-08-07 07:03:46]

Change committed as 150294