Add a count() func for calculated traces that simply counts the non-1e100 values.

BUG=skia:

Review URL: https://codereview.chromium.org/732413003
Added log statement and switched to caching expectations store

BUG=skia:2930
TBR=jcgregorio

Review URL: https://codereview.chromium.org/740533002
Update CT's create pagesets task to capture the new set of pagesets.
Also deleted unused pageset types.

TBR=borenet
BUG=skia:3140

Review URL: https://codereview.chromium.org/735693003