Use null rather than empty frame to lock Surface resources

Use null rather than empty frame to lock Surface resources

This will allow the DisplayScheduler to differentiate between
a frame without any resources and one that should not be drawn.

Some tests use frames without any resources and the DisplayScheduler
was missinterpreting that as the Browser locking resources.

BUG=467750
Committed: https://crrev.com/5e5956af406aec997246697735a11f4222d83bef
Cr-Commit-Position: refs/heads/master@{#324765}

[brianderson, 2015-04-10 21:30:47]

brianderson@chromium.org changed reviewers:
+ jbauman@chromium.org

[brianderson, 2015-04-10 21:30:47]

Is this sane?

This helps fix the failures I was seeing with
https://codereview.chromium.org/1012853003 on the
RenderWidgetHostViewAuraTest.Resize test, which had frames without any resources
but was expecting them not to be locked by the Browser.

[jbauman, 2015-04-10 21:34:58]

lgtm, with one change, as long as this doesn't hit DCHECKs anywhere.

https://codereview.chromium.org/1073323002/diff/1/cc/surfaces/surface.cc
File cc/surfaces/surface.cc (right):

https://codereview.chromium.org/1073323002/diff/1/cc/surfaces/surface.cc#newc...
cc/surfaces/surface.cc:45: if (current_frame_) {
This should be frame, not current_frame_.

[brianderson, 2015-04-11 00:23:04]

The CQ bit was checked by brianderson@chromium.org

[brianderson, 2015-04-11 00:23:04]

The patchset sent to the CQ was uploaded after l-g-t-m from jbauman@chromium.org
Link to the patchset: https://codereview.chromium.org/1073323002/#ps20001
(title: "current_frame -> frame")

[commit-bot: I haz the power, 2015-04-11 00:24:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1073323002/20001

[commit-bot: I haz the power, 2015-04-11 03:19:34]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-11 03:20:32]

Patchset 2 (id:??) landed as
https://crrev.com/5e5956af406aec997246697735a11f4222d83bef
Cr-Commit-Position: refs/heads/master@{#324765}

[brianderson, 2015-04-14 19:14:28]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/1088883004/ by brianderson@chromium.org.

The reason for reverting is: This is causing timeouts on the gpu bots:
https://code.google.com/p/chromium/issues/detail?id=476544#c5.

[brianderson, 2015-04-15 23:23:35]

ptal

[jbauman, 2015-04-15 23:24:35]

lgtm

[brianderson, 2015-04-15 23:29:22]

Couldn't commit for some reason. Moving to:
https://codereview.chromium.org/1084313002