Add unit tests for nonuniform GPU memmgr policy

Add unit tests for nonuniform GPU memmgr policy.

Add a default memory allocation level for clients that have
not yet sent memory usage levels to the manager. This default
is currently set to equal the minimum, but the minimum will
be lowered substantially in the future (and the default will stay
higher, to avoid a low-res flicker at load).

Change GetMinimumClientAllocation to always use a value set
during initialization instead of having a separate override flag.

Fix a comparison bug that caused no clients to retain their
memory when made nonvisible.

Make clients that are nonvisible and have had their memory
evicted not be given a budget that gives them back their memory
until they are made visible again. This prevents situations where
we burn resources painting-then-freeing resources for
backgrounded clients.

BUG=168413
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=180054

[ccameron, 2013-01-30 03:10:41]

After this I won't be too afraid of switching the memmgr over to the impl-side
policy (the new tests already found bugs, so terror was appropriate), and adding
a flag to switch to the old one.

[ccameron, 2013-01-30 21:03:19]

https://codereview.chromium.org/12087078/diff/7/content/common/gpu/gpu_memory...
File content/common/gpu/gpu_memory_manager.h (right):

https://codereview.chromium.org/12087078/diff/7/content/common/gpu/gpu_memory...
content/common/gpu/gpu_memory_manager.h:105: DefaultAllocation);
This list is getting fairly absurdly long.  There was the alternative of
friending the base class (GpuMemoryManagerTextNonuniform) and then adding hooks
in the base class for the derived tests to call.  That would be less messy IMO,
but my understanding is that the existing is the preferred mechanism.

[ccameron, 2013-01-31 18:13:49]

Ping.

[nduca, 2013-01-31 19:48:59]

lgtm

[ccameron, 2013-01-31 22:55:39]

Thanks!

piman, can you do an OWNER review?

[piman, 2013-01-31 23:10:17]

lgtm

[ccameron, 2013-01-31 23:50:15]

Thanks!!

[commit-bot: I haz the power, 2013-02-01 00:23:47]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ccameron@chromium.org/12087078/7

[commit-bot: I haz the power, 2013-02-01 03:19:08]

Change committed as 180054