Allow the native theme to paint the corner between scrollbars

For the Mac port of views, we need to draw the corner part to connect the
vertical and horizontal tracks together.
Update ScrollView to allow the native theme to paint the corner square when
both horizontal and vertical scrollbars are showing.
This is done by installing a view at the corner and have it call
NativeTheme::Paint(..).

BUG=401346
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289483

[Andre, 2014-08-12 23:55:05]

sky@ PTAL.
For MacViews I need to paint the corner square to emulate the native Mac look.

https://codereview.chromium.org/462373002/diff/1/ui/native_theme/native_theme...
File ui/native_theme/native_theme_base.cc (left):

https://codereview.chromium.org/462373002/diff/1/ui/native_theme/native_theme...
ui/native_theme/native_theme_base.cc:526: canvas->drawIRect(RectToSkIRect(rect),
paint);
Now that this is called, changed it to paint nothing to preserve current
behavior.

https://codereview.chromium.org/462373002/diff/1/ui/views/controls/scroll_view.h
File ui/views/controls/scroll_view.h (right):

https://codereview.chromium.org/462373002/diff/1/ui/views/controls/scroll_vie...
ui/views/controls/scroll_view.h:138: View* corner_view_;
Renamed this since I don't think this is related to resize at all?

[Andre, 2014-08-13 00:10:18]

I wanted to test this in ScrollViewTest, but corner_view_ feels like an
implementation detail that should not be exposed in the public API.
Making the test a friend and accessing corner_view_ directly did not seem ideal
either.
Let me know what you think.

[sky, 2014-08-13 03:33:11]

How about setting an id on the corner_view_ that you can use to get at it.

https://codereview.chromium.org/462373002/diff/1/ui/views/controls/scroll_vie...
File ui/views/controls/scroll_view.cc (right):

https://codereview.chromium.org/462373002/diff/1/ui/views/controls/scroll_vie...
ui/views/controls/scroll_view.cc:47: };
private: DISALLOW...

[Andre, 2014-08-13 17:53:36]

Thanks Scott.
For the test, I decided to look for the corner view based on its expected
bounds,
PTAL.

https://codereview.chromium.org/462373002/diff/1/ui/views/controls/scroll_vie...
File ui/views/controls/scroll_view.cc (right):

https://codereview.chromium.org/462373002/diff/1/ui/views/controls/scroll_vie...
ui/views/controls/scroll_view.cc:47: };
On 2014/08/13 03:33:11, sky wrote:
> private: DISALLOW...

Done.

[sky, 2014-08-13 19:51:10]

https://codereview.chromium.org/462373002/diff/40001/ui/views/controls/scroll...
File ui/views/controls/scroll_view_unittest.cc (right):

https://codereview.chromium.org/462373002/diff/40001/ui/views/controls/scroll...
ui/views/controls/scroll_view_unittest.cc:354: View* corner_view = NULL;
Ick! I would prefer you expose the corner view for testing.

[Andre, 2014-08-13 22:12:39]

https://codereview.chromium.org/462373002/diff/40001/ui/views/controls/scroll...
File ui/views/controls/scroll_view_unittest.cc (right):

https://codereview.chromium.org/462373002/diff/40001/ui/views/controls/scroll...
ui/views/controls/scroll_view_unittest.cc:354: View* corner_view = NULL;
On 2014/08/13 19:51:10, sky wrote:
> Ick! I would prefer you expose the corner view for testing.

Done, thanks.
I tried using set_id(), but seems like if we make the id public then we might as
well add a public getter for the corner view.
I'm making the test a friend in the latest patch, let me know if you prefer a
public getter instead.

[sky, 2014-08-13 22:48:36]

LGTM

[Andre, 2014-08-13 22:49:44]

The CQ bit was checked by andresantoso@chromium.org

[commit-bot: I haz the power, 2014-08-13 22:54:10]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/andresantoso@chromium.org/462373002/60001

[commit-bot: I haz the power, 2014-08-14 07:56:08]

Committed patchset #3 (60001) as 289483