Currently, the number of ticks to wait before optimizing is a constant (if
sufficient feedback is available). This cl changes it so that, larger
functions would have to wait longer for optimizing. The number of ticks
required scales linearly with the function size.

Bug: 
Change-Id: Id27bea715cf15960667cf63381b1cbe8dac94428
Reviewed-on: https://chromium-review.googlesource.com/538614
Commit-Queue: Mythri Alle <mythria@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46097}