Update GatherPixelRefDevice to the new SkImage/SkPixelRef API

Update GatherPixelRefDevice to the new SkImage/SkPixelRef API

Blink is no longer using pixel ref URIs to label lazy decoded images, so the URI-based heuristic is
obsolete.  Instead, use new SkPixelRef/SkImage isLazyGenerated() method.

Also add missing drawImage & drawImageRect overrides + unit tests (similar to their drawBitmap,
drawBitmapRect counterparts).

BUG=skia:4224
R=reed@google.com,robertphillips@google.com
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/73df5c7ea28af683ee3235c6bf34b50e3f9b77d9
Cr-Commit-Position: refs/heads/master@{#344818}

[f(malita), 2015-08-20 20:48:15]

fmalita@chromium.org changed reviewers:
+ reed@google.com, robertphillips@google.com, vmpstr@chromium.org

[reed1, 2015-08-20 20:58:24]

reed@google.com changed required reviewers:
+ vmpstr@chromium.org

[reed1, 2015-08-20 20:58:25]

lgtm

[vmpstr, 2015-08-20 21:11:17]

lgtm, thanks!

[f(malita), 2015-08-21 08:37:47]

On 2015/08/20 21:11:17, vmpstr wrote:
> lgtm, thanks!

Patch set #1 missed a bunch of cc unit tests relying on the old URI label. 
Updated, PTAL.

[reed1, 2015-08-21 15:16:18]

lgtm

[f(malita), 2015-08-21 18:14:04]

The CQ bit was checked by fmalita@chromium.org

[f(malita), 2015-08-21 18:14:05]

The patchset sent to the CQ was uploaded after l-g-t-m from vmpstr@chromium.org
Link to the patchset: https://codereview.chromium.org/1294673006/#ps20001
(title: "update cc_unittests")

[commit-bot: I haz the power, 2015-08-21 18:14:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1294673006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1294673006/20001

[commit-bot: I haz the power, 2015-08-21 18:21:29]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-21 18:22:06]

Patchset 2 (id:??) landed as
https://crrev.com/73df5c7ea28af683ee3235c6bf34b50e3f9b77d9
Cr-Commit-Position: refs/heads/master@{#344818}