Check for null renderer string when checking ANGLE GL info

Bug: chromium:915596
Change-Id: I9e19bf2d27f15f246cfcdcbfd6379785e258b284
Reviewed-on: https://skia-review.googlesource.com/c/178921
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
1 file changed