[Aura] Support transparent webkit.

[Aura] Support transparent webkit.

Support turning on webkit transparency by setting a background image.
- Update RenderWidget::PaintRect to handle background transparency;
- Update BackingStoreSkia::PaintToBackingStore to handle webkit transparency;
- Turn on compositing of RenderWidgetHostViewAura's layer when we set a background with transparency;

BUG=98311
TEST=Verify when applist change (chromium:98308) is in.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=106943

[xiyuan, 2011-10-21 20:12:46]

+jam

Jam, could you help to review this in case brettw does not have time?

[brettw, 2011-10-21 20:14:43]

lgtm

http://codereview.chromium.org/8369006/diff/1/content/browser/renderer_host/b...
File content/browser/renderer_host/backing_store_skia.cc (right):

http://codereview.chromium.org/8369006/diff/1/content/browser/renderer_host/b...
content/browser/renderer_host/backing_store_skia.cc:77:
canvas_.get()->drawBitmapRect(sk_bitmap, &srcrect, dstrect, &copy_paint_);
In other places we haven't bothered saving the SkPaint. I'd probably just create
it on the stack when you need it, unless you have a strong reason to do it like
this.

[xiyuan, 2011-10-21 20:24:05]

Thanks for the quick review. :)

http://codereview.chromium.org/8369006/diff/1/content/browser/renderer_host/b...
File content/browser/renderer_host/backing_store_skia.cc (right):

http://codereview.chromium.org/8369006/diff/1/content/browser/renderer_host/b...
content/browser/renderer_host/backing_store_skia.cc:77:
canvas_.get()->drawBitmapRect(sk_bitmap, &srcrect, dstrect, &copy_paint_);
On 2011/10/21 20:14:44, brettw wrote:
> In other places we haven't bothered saving the SkPaint. I'd probably just
create
> it on the stack when you need it, unless you have a strong reason to do it
like
> this.

Done.

[commit-bot: I haz the power, 2011-10-22 05:34:49]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xiyuan@chromium.org/8369006/6001

[commit-bot: I haz the power, 2011-10-22 08:32:36]

The commit queue went berserk retrying too often for a
seemingly flaky test. Builder is win_rel, revision is 106848, job name
was 8369006-6001 (retry) (retry) (retry) (retry).

[commit-bot: I haz the power, 2011-10-22 15:22:22]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xiyuan@chromium.org/8369006/6001

[commit-bot: I haz the power, 2011-10-22 18:03:44]

The commit queue went berserk retrying too often for a
seemingly flaky test. Builder is win_rel, revision is 106859, job name
was 8369006-6001 (retry) (retry) (retry) (retry).

[commit-bot: I haz the power, 2011-10-24 16:38:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xiyuan@chromium.org/8369006/6001

[commit-bot: I haz the power, 2011-10-24 17:54:21]

Change committed as 106943