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- When calculating the maximum animation to screen scale, for a nested
  or unknown-scale transform animation, use the parent's maximum
  animation scale instead of kInvalidScale which would fallback to
  page_scale * device_scale which ignored ancestor scales.

- When adjusting raster scale for transform animation, use
  max(raster_contents_scale_, maximum_animation_scale).
  In normal cases, if the former is bigger than the latter, it means
  that raster_contents_scale_ calculated when the animation starts is
  more accurate than the maximum_animation_scale calculated by the
  cc/animation subsystem.

- In case that a bigger scale than 1.5x of the previous calculated
  animation scale, force an raster scale. The case should be rare.

Bug: 1165408
Change-Id: Ieccdb9e16fb6f151e74a881855ce3655e857c372
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633800Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844899}