Support plumbing LatencyInfo through the old software path.

Support plumbing LatencyInfo through the old software path.

This allows us to collect latency stats with 3d disabled.

BUG=155367
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=205011

[piman, 2013-06-07 02:51:30]

LGTM overall, with a couple of uestions.

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
File content/browser/renderer_host/render_widget_host_view_aura.cc (right):

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
content/browser/renderer_host/render_widget_host_view_aura.cc:1036:
software_latency_info_.MergeWith(latency_info);
Does this grow arbitrarily? If the tab is updating while offscreen, I'm afraid
we won't be calling OnPaint. Can this be a problem?

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
File content/browser/renderer_host/render_widget_host_view_gtk.cc (right):

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
content/browser/renderer_host/render_widget_host_view_gtk.cc:1217:
render_widget_host->FrameSwapped(software_latency_info_);
So compared to the hardware path, this can somewhat misleading because this just
sent the command to X but we don't know when it'll be on screen really.
It's probably ok as a first step, but have we measured the delta? so that we can
normalize the typical latency expectation when comparing HW vs SW.

[jbauman, 2013-06-07 07:28:24]

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
File content/browser/renderer_host/render_widget_host_view_aura.cc (right):

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
content/browser/renderer_host/render_widget_host_view_aura.cc:1036:
software_latency_info_.MergeWith(latency_info);
On 2013/06/07 02:51:30, piman wrote:
> Does this grow arbitrarily? If the tab is updating while offscreen, I'm afraid
> we won't be calling OnPaint. Can this be a problem?

No, this structure was designed not to grow, for this very reason.

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
File content/browser/renderer_host/render_widget_host_view_gtk.cc (right):

https://codereview.chromium.org/15682010/diff/9001/content/browser/renderer_h...
content/browser/renderer_host/render_widget_host_view_gtk.cc:1217:
render_widget_host->FrameSwapped(software_latency_info_);
On 2013/06/07 02:51:30, piman wrote:
> So compared to the hardware path, this can somewhat misleading because this
just
> sent the command to X but we don't know when it'll be on screen really.
> It's probably ok as a first step, but have we measured the delta? so that we
can
> normalize the typical latency expectation when comparing HW vs SW.

Well, even in the hardware path we don't know when the actual swap to the screen
occurs - particularly when there's an external compositor.

I generally haven't worried too much about the precise amount of latency that we
can't measure, because that's very system-dependent (touchpad controller
latency, compositing window manager vs. not) and there's not that much we can do
about it. However, I think it wouldn't be hard to compare against our
camera-based measurements to see how much is being missed here.

[jbauman, 2013-06-08 00:28:49]

Adding jschuh@ to rubber-stamp the IPC change.

[jschuh, 2013-06-08 00:41:21]

lgtm

[commit-bot: I haz the power, 2013-06-08 00:54:46]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jbauman@chromium.org/15682010/9001

[commit-bot: I haz the power, 2013-06-08 04:39:12]

Change committed as 205011