Fix SkComposeImageFilter's bounds computation and offset handling

Fix SkComposeImageFilter's bounds computation and offset handling

This makes SkComposeImageFilter::computeFastBounds compose its
filters' bounds (rather than falling back to
SkImageFilter::computeFastBounds, which takes the union of the bounds).

This also makes SkComposeImageFilter::onFilterImage correctly handle
an offset produced when applying the inner filter; such offsets were
previously ignored.

BUG=chromium:453924
Committed: https://skia.googlesource.com/skia/+/5788faaa2ac4203827c68006b669e277d441e2e4

[ajuma, 2015-02-10 20:26:15]

ajuma@chromium.org changed reviewers:
+ reed@google.com

[ajuma, 2015-02-10 20:27:22]

There were the bugs I was referring to in the Slimming Paint meeting yesterday.

[reed1, 2015-02-12 21:01:18]

reed@google.com changed reviewers:
+ senorblanco@google.com

[reed1, 2015-02-12 21:01:19]

seems fine, adding senor

https://codereview.chromium.org/908273002/diff/1/src/effects/SkComposeImageFi...
File src/effects/SkComposeImageFilter.cpp (right):

https://codereview.chromium.org/908273002/diff/1/src/effects/SkComposeImageFi...
src/effects/SkComposeImageFilter.cpp:42: if (!outer->filterImage(proxy, tmp,
outerContext, result, &outerOffset))
nit: Skia style always uses { }

[ajuma, 2015-02-13 16:02:24]

https://codereview.chromium.org/908273002/diff/1/src/effects/SkComposeImageFi...
File src/effects/SkComposeImageFilter.cpp (right):

https://codereview.chromium.org/908273002/diff/1/src/effects/SkComposeImageFi...
src/effects/SkComposeImageFilter.cpp:42: if (!outer->filterImage(proxy, tmp,
outerContext, result, &outerOffset))
On 2015/02/12 21:01:19, reed1 wrote:
> nit: Skia style always uses { }

Done.

[reed1, 2015-02-13 16:12:48]

lgtm

[ajuma, 2015-02-13 16:20:38]

The CQ bit was checked by ajuma@chromium.org

[commit-bot: I haz the power, 2015-02-13 16:20:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/908273002/20001

[commit-bot: I haz the power, 2015-02-13 17:05:51]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/5788faaa2ac4203827c68006b669e277d441e2e4