Make test playback more robust.

Ensures that chart viewport size is fixed on all platforms before we reset
axes range so that we get reproducible results.

Change-Id: I7c94b1d6bdb274479ea9b6b1d3f2c8d26f5b62cd
Merge topic '13818_fix_plot_min_max' into next

3b9ab1b Make test playback more robust.