[SP] Always paint whole non-custom scrollbars

[SP] Always paint whole non-custom scrollbars

We use the scrollbar as the display item client for paintings of
a non-custom scrollbar. This requires us always paint the whole scrollbar
or paint nothing.

BUG=496239
TEST=fast/scrolling/scrollbar-repaint-two-level-scrollable.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196438

[Xianzhu, 2015-06-03 19:35:17]

wangxianzhu@chromium.org changed reviewers:
+ chrishtr@chromium.org, pdr@chromium.org

[chrishtr, 2015-06-03 21:19:21]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2015-06-03 21:19:21]

lgtm

https://codereview.chromium.org/1142283006/diff/1/Source/platform/graphics/pa...
File Source/platform/graphics/paint/DisplayItemList.cpp (left):

https://codereview.chromium.org/1142283006/diff/1/Source/platform/graphics/pa...
Source/platform/graphics/paint/DisplayItemList.cpp:249: // else: do nothing
because previously the client generated a empty picture which is not stored in
the cache.
The behavior this comment refers to was removed earlier?

[commit-bot: I haz the power, 2015-06-03 21:20:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1142283006/1

[Xianzhu, 2015-06-03 21:32:57]

https://codereview.chromium.org/1142283006/diff/1/Source/platform/graphics/pa...
File Source/platform/graphics/paint/DisplayItemList.cpp (left):

https://codereview.chromium.org/1142283006/diff/1/Source/platform/graphics/pa...
Source/platform/graphics/paint/DisplayItemList.cpp:249: // else: do nothing
because previously the client generated a empty picture which is not stored in
the cache.
On 2015/06/03 21:19:21, chrishtr wrote:
> The behavior this comment refers to was removed earlier?

Yes. I should have changed the above when I added back dummy display items.

[commit-bot: I haz the power, 2015-06-03 22:46:09]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196438