Revert of Fix crash when we don't have a plane to display (patchset #2 id:20001 of...

Revert of Fix crash when we don't have a plane to display (patchset #2 id:20001 of https://codereview.chromium.org/779173007/)

Reason for revert:
Broke Linux ChromiumOS Ozone.
http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Ozone%20Builder/builds/8423

GetPrimaryPlane was changed to return a pointer, but a callsite was
not modified.

Original issue's description:
> Fix crash when we don't have a plane to display
>
> BUG=434115,438835
>
> Committed: https://crrev.com/208e6bf151685abc68ac836db5afb3543d8a1e92
> Cr-Commit-Position: refs/heads/master@{#308105}

TBR=dnicoara@chromium.org,achaulk@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=434115,438835

Review URL: https://codereview.chromium.org/800053002

Cr-Commit-Position: refs/heads/master@{#308118}