Modify LineBench for drawing

Currently we only have benchmark for lines that contains randomly generated
points. This CL modifies the benchmark which adds cases of drawing straight
lines. Also, this CL changes the call from drawPoints() to drawLines()
which measures the performance of line drawing.

BUG=skia:5243
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1936153002

Review-Url: https://codereview.chromium.org/1936153002
1 file changed