Add SurfaceDisplayOutputSurface unittests

Add SurfaceDisplayOutputSurface unittests

Three basic tests added:
1) DamageTriggersSwapBuffers
2) NoDamageDoesNotTriggerSwapBuffers
3) LockingResourcesDoesIndirectlyCauseDamage

The last test is a regression test to make sure we
don't accidentally damage the root surface every frame.
It fails with the following patch applied, which
got reverted:
https://codereview.chromium.org/1073323002

BUG=476544
Committed: https://crrev.com/8eaf23b2f5ed71c59d6597f90dbf5d2409e36e55
Cr-Commit-Position: refs/heads/master@{#329991}

[brianderson, 2015-05-12 03:25:28]

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

[brianderson, 2015-05-12 03:25:28]

ptal!

[brianderson, 2015-05-12 17:01:20]

https://codereview.chromium.org/1124273004/diff/40001/cc/surfaces/surface_dis...
File cc/surfaces/surface_display_output_surface_unittest.cc (right):

https://codereview.chromium.org/1124273004/diff/40001/cc/surfaces/surface_dis...
cc/surfaces/surface_display_output_surface_unittest.cc:47: class
TestSurfaceDisplayOutputSurface : public SurfaceDisplayOutputSurface {
I guess this class is pretty useless for the existing tests. I'm going to remove
it unless there are any tests I should add that could use it.

[brianderson, 2015-05-14 23:24:04]

Found the uninitialized variable - it was coming up as 0 on my Windows machine
(causing the tests t fail), but random data on my Linux machine (allowing the
tests to pass).

I think this is ready now - ptal.

[jbauman, 2015-05-14 23:29:55]

lgtm

[brianderson, 2015-05-14 23:35:38]

The CQ bit was checked by brianderson@chromium.org

[commit-bot: I haz the power, 2015-05-14 23:37:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1124273004/140001

[commit-bot: I haz the power, 2015-05-15 00:24:14]

Committed patchset #8 (id:140001)

[commit-bot: I haz the power, 2015-05-15 00:25:22]

Patchset 8 (id:??) landed as
https://crrev.com/8eaf23b2f5ed71c59d6597f90dbf5d2409e36e55
Cr-Commit-Position: refs/heads/master@{#329991}