ui: Make compositor unittests access the canvas through PaintRecorder.

ui: Make compositor unittests access the canvas through PaintRecorder.

Don't access the canvas() through the PaintContext, to allow the
PaintContext to be backed by a DisplayItemList instead of a Canvas in
the future.

R=piman@chromium.org, sadrul
BUG=466426
Committed: https://crrev.com/c73232294c5510e8f05e61b48708b7c2f48faae3
Cr-Commit-Position: refs/heads/master@{#324120}

[danakj, 2015-04-07 19:00:29]

Sadrul you're not an owner here, but I am and I thought you might be a good
reviewer?

[sadrul, 2015-04-07 19:05:12]

lgtm

https://codereview.chromium.org/1064103002/diff/1/ui/compositor/paint_context.h
File ui/compositor/paint_context.h (right):

https://codereview.chromium.org/1064103002/diff/1/ui/compositor/paint_context...
ui/compositor/paint_context.h:70: const gfx::Rect& InvalidationForTesting()
const { return invalidation_; }
In a number of components, we expose such things through a TestApi (grep for
TestApi in //ui/) instead of *ForTesting() methods to avoid misuse/accidental
use of test-apis in real code.

[piman, 2015-04-07 19:27:20]

lgtm

[danakj, 2015-04-07 20:09:35]

https://codereview.chromium.org/1064103002/diff/1/ui/compositor/paint_context.h
File ui/compositor/paint_context.h (right):

https://codereview.chromium.org/1064103002/diff/1/ui/compositor/paint_context...
ui/compositor/paint_context.h:70: const gfx::Rect& InvalidationForTesting()
const { return invalidation_; }
On 2015/04/07 19:05:12, sadrul wrote:
> In a number of components, we expose such things through a TestApi (grep for
> TestApi in //ui/) instead of *ForTesting() methods to avoid misuse/accidental
> use of test-apis in real code.

FWIW Presubmit makes an error if you use a method named ForTesting in a non-test
file.

I wanted to subclass but then I'd have to inject a testing PaintContext into
ui::Layer. I guess a friend class would work too, hm. That's slightly nicer as
it keeps more code/api out of prod. But it also moves access to private things
somewhere else, hm hm.

I think I'll go with it as this for now.. but I wanna think about this TestAPI
idea, thanks for pointing it out.

[danakj, 2015-04-07 20:09:39]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2015-04-07 20:10:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1064103002/1

[commit-bot: I haz the power, 2015-04-07 21:09:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-07 21:11:30]

Patchset 1 (id:??) landed as
https://crrev.com/c73232294c5510e8f05e61b48708b7c2f48faae3
Cr-Commit-Position: refs/heads/master@{#324120}