GitLab

Move the core routine that handles the complicated case where the play
back rate is not 1 or interpolation/extrapolation is needed.

Then break out that routine into two new routines for computing the
indices and for computing the output so that we can optimize each
independently.

A slight function difference occurred because we changed the
interpolation formula from using (1-f)*x0+f*x1 to x0+f*(x1-x0).  This
is mathematically equivalent and but not in floating point.  This
shows up in the one test needing the threshold to be updated slightly.

Bug: 1104371
Change-Id: Id299fb9471d01edad8d9c9da73084af9a53533f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342136Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Reviewed-by: Raymond Toy <rtoy@chromium.org>
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797065}