platform_graphics: fix gonum-plot API breakage

Newer versions of gonum-plot have removed the error return
value from their plot.New(). There is very little context
why they did it, but changes have been done in the entire
codebase to drop it, for eg see upstream commit:

commit e331c55ac6e2923dc189213cd771cbdcbe350383
Author: Sebastien Binet <>
Date:   Sat Feb 6 16:19:59 2021 +0100

    all: introduce no-err New plot function

So we also drop the err return value.

TEST=Local builds in GOPATH/modules mode on x64, arm.

Cq-Depend: chromium:3652421
Change-Id: I50f3eb669f5981e90a6b17a2e5e33b4dfbd988ce
Auto-Submit: Adrian Ratiu <>
Tested-by: Adrian Ratiu <>
Commit-Queue: Adrian Ratiu <>
Tested-by: Manoj Gupta <>
Reviewed-by: Po-Hsien Wang <>
1 file changed