Pass a ui::PaintContext from ui::Layer to layer delegates.

Pass a ui::PaintContext from ui::Layer to layer delegates.

This is a plumbing CL to create a ui::PaintContext that wraps a
gfx::Canvas up in ui::Layer. This is passed to every LayerDelegate,
and also through to aura::WindowDelegates and
views::NativeWidgetDelegates to eventually reach views::View as well.

This way ui::PaintContext is created in one place (for compositor
paints, there are other places painting to bitmaps we'll address
later). And in the future the ui::PaintContext can be backed by a
display list instead of a canvas.

R=sky
BUG=466426
Committed: https://crrev.com/85d970e4cc6d5f71c30a94cd31d6f0fa07b38890
Cr-Commit-Position: refs/heads/master@{#323855}

[danakj, 2015-04-02 20:59:33]

danakj@chromium.org changed reviewers:
+ piman@chromium.org

[danakj, 2015-04-02 20:59:34]

Sorry for yet another plumbing CL. This should get us through all of that mess,
and let us start working on backing the PaintContext by a display list.

This is just passing a PaintContext from ui::Layer instead of making it in
Widget::OnPaintNativeWidget and View::OnPaintLayer.

[piman, 2015-04-02 21:16:50]

LGTM for content/ and ui/compositor

[sky, 2015-04-02 23:33:43]

LGTM

[danakj, 2015-04-03 19:54:19]

The CQ bit was checked by danakj@chromium.org

[danakj, 2015-04-03 19:54:20]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org,
piman@chromium.org
Link to the patchset: https://codereview.chromium.org/1057873004/#ps20001
(title: "layer-paintcontext: .")

[commit-bot: I haz the power, 2015-04-03 19:54:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057873004/20001

[commit-bot: I haz the power, 2015-04-03 20:00:35]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-03 20:00:37]

Try jobs failed on following builders:
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[danakj, 2015-04-03 20:07:38]

The CQ bit was checked by danakj@chromium.org

[danakj, 2015-04-03 20:07:38]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org,
piman@chromium.org
Link to the patchset: https://codereview.chromium.org/1057873004/#ps40001
(title: "layer-paintcontext: rebase")

[commit-bot: I haz the power, 2015-04-03 20:08:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057873004/40001

[commit-bot: I haz the power, 2015-04-03 20:25:31]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-03 20:25:33]

Try jobs failed on following builders:
  linux_chromium_gn_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[danakj, 2015-04-03 20:30:33]

The CQ bit was checked by danakj@chromium.org

[danakj, 2015-04-03 20:30:34]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org,
piman@chromium.org
Link to the patchset: https://codereview.chromium.org/1057873004/#ps60001
(title: "layer-paintcontext: .")

[commit-bot: I haz the power, 2015-04-03 20:31:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057873004/60001

[commit-bot: I haz the power, 2015-04-03 20:48:50]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-03 20:48:52]

Try jobs failed on following builders:
  linux_chromium_gn_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[danakj, 2015-04-03 20:50:50]

The CQ bit was checked by danakj@chromium.org

[danakj, 2015-04-03 20:50:51]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org,
piman@chromium.org
Link to the patchset: https://codereview.chromium.org/1057873004/#ps80001
(title: "layer-paintcontext: .")

[commit-bot: I haz the power, 2015-04-03 20:51:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057873004/80001

[commit-bot: I haz the power, 2015-04-03 21:09:28]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-03 21:09:30]

Try jobs failed on following builders:
  linux_chromium_gn_chromeos_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_gn_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[danakj, 2015-04-03 22:02:37]

The CQ bit was checked by danakj@chromium.org

[danakj, 2015-04-03 22:02:38]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org,
piman@chromium.org
Link to the patchset: https://codereview.chromium.org/1057873004/#ps100001
(title: "layer-paintcontext: .")

[commit-bot: I haz the power, 2015-04-03 22:03:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057873004/100001

[commit-bot: I haz the power, 2015-04-03 22:36:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-03 22:36:38]

Try jobs failed on following builders:
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[danakj, 2015-04-03 22:38:43]

The CQ bit was checked by danakj@chromium.org

[danakj, 2015-04-03 22:38:43]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org,
piman@chromium.org
Link to the patchset: https://codereview.chromium.org/1057873004/#ps120001
(title: "layer-paintcontext: mac")

[commit-bot: I haz the power, 2015-04-03 22:39:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057873004/120001

[commit-bot: I haz the power, 2015-04-04 00:15:39]

Committed patchset #7 (id:120001)

[commit-bot: I haz the power, 2015-04-04 00:16:22]

Patchset 7 (id:??) landed as
https://crrev.com/85d970e4cc6d5f71c30a94cd31d6f0fa07b38890
Cr-Commit-Position: refs/heads/master@{#323855}