Move all the page actions from repaint measurements to repaint pages.
This is due to 2 reasons:
+ Page specific logic should belong to page, not page test.
+ Simplify the repaint measurement control code, which make
it easier to port repaint to TimelineBasedMeasurement.
Trybot link for repaint.gpu_rasterization.key_mobile_sites_repaint:
https://codereview.chromium.org/
1098543002
BUG=444703, 455391
Review URL: https://codereview.chromium.org/
1089223003
Cr-Commit-Position: refs/heads/master@{#325558}