Fix bug testing SkCodec for ICO

Fix bug testing SkCodec for ICO

Looking in Gold, I see some ICO images that only show the upper left
corner of the originals. It is happening because we use different ways
of deciding what the dimensions are:

In CodecSrc::size(), we use an SkScaledCodec to get the dimensions,
even when fMode is not kScaledCodec_Mode.

In CodecSrc::draw(), we only use SkScaledCodec in kScaledCodec_Mode.

My recent CL to combine SkScanlineDecoder with SkCodec revealed this
bug, because now SkScaledCodec::NewFromStream will succeed on ICO.
(Previously, it failed because we do not yet have a scanline decoder
for ICO (skbug.com/4404). Now that they are combined, we would need
to specially flag ICO to stop returning an SkScaledCodec.)

Switch size() to use the correct type of codec.

Committed: https://skia.googlesource.com/skia/+/7fac5af5e9310826721ff416bdbe71294d607b2a

[scroggo, 2015-09-30 18:17:53]

scroggo@google.com changed reviewers:
+ msarett@google.com

[scroggo, 2015-09-30 18:17:53]

Matt,

I think this is a good change regardless, but we could independently fix the bug
by making SkScaledCodec check for kICO_SkEncodedFormat and return nullptr for
that type. This would be temporary, though, until we implement ICO scanline
decoding (skbug.com/4404).

[msarett, 2015-09-30 18:19:57]

lgtm

[scroggo, 2015-09-30 18:25:50]

The CQ bit was checked by scroggo@google.com

[commit-bot: I haz the power, 2015-09-30 18:26:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1373253004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1373253004/1

[commit-bot: I haz the power, 2015-09-30 18:33:17]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/7fac5af5e9310826721ff416bdbe71294d607b2a