ash: Clean up system background layer.

ash: Clean up system background layer.

This adds a SystemBackgroundController class that's
responsible for a ui::Layer that's stacked underneath all
other layers.

I'm also adding an --ash-copy-host-background-at-boot flag
that can be set to instruct the controller to copy the host
window's content into the system background layer at
startup; otherwise, we display the same background color
used by Chrome OS's boot splash screen.

I suspect that there's a small performance hit from copying
(I've seen the XGetImage() take between 25 and 170 ms
depending on hardware), although it seems to be hidden in
the noise of our total boot times.  Regardless, I figure
that we should only turn this on right now for systems that
need it (to hide an even-longer delay where the compositor
is drawing but the login background images hasn't been
loaded).

In any case, once the login background is visible, the
system background layer is reset to display the black
background that's needed for fullscreen animations that
manipulate the desktop background (for the workspace or
power button).

BUG=152309
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=164704

[Daniel Erat, 2012-10-26 00:41:15]

https://codereview.chromium.org/11273059/diff/4001/ui/aura/root_window_host_l...
File ui/aura/root_window_host_linux.cc (right):

https://codereview.chromium.org/11273059/diff/4001/ui/aura/root_window_host_l...
ui/aura/root_window_host_linux.cc:751: bool
RootWindowHostLinux::DispatchEventForRootWindow(
sorry, moved this code without any changes to it to match the header order; will
move back for this change if you want

[sky, 2012-10-26 19:51:33]

LGTM

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
File ash/wm/system_background_controller.cc (right):

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:36: ~HostContentLayerDelegate() {}
virtual

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:92: default:
nit: add CONTENT_INVALID and remove the default so you get a compile error when
a new type is added.

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:106: layer_delegate_.reset(new
HostContentLayerDelegate(root_window_));
Since layer_ references layer_delegate_ can you delete layer_ before
layer_delegate_.

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:122:
layer->SetBounds(root_window_->layer()->bounds());
SetBounds(gfx::Rect(root_window_->layer()->bounds().size());

[Daniel Erat, 2012-10-29 15:50:32]

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
File ash/wm/system_background_controller.cc (right):

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:36: ~HostContentLayerDelegate() {}
On 2012/10/26 19:51:33, sky wrote:
> virtual

Done.

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:92: default:
On 2012/10/26 19:51:33, sky wrote:
> nit: add CONTENT_INVALID and remove the default so you get a compile error
when
> a new type is added.

Done.

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:106: layer_delegate_.reset(new
HostContentLayerDelegate(root_window_));
On 2012/10/26 19:51:33, sky wrote:
> Since layer_ references layer_delegate_ can you delete layer_ before
> layer_delegate_.

Done (heh, did this at first but figured I was being paranoid).

https://codereview.chromium.org/11273059/diff/7001/ash/wm/system_background_c...
ash/wm/system_background_controller.cc:122:
layer->SetBounds(root_window_->layer()->bounds());
On 2012/10/26 19:51:33, sky wrote:
> SetBounds(gfx::Rect(root_window_->layer()->bounds().size());

Whoops, thanks.  Done.

[commit-bot: I haz the power, 2012-10-29 17:18:03]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/derat@chromium.org/11273059/13029

[commit-bot: I haz the power, 2012-10-29 19:22:21]

Change committed as 164704