Reland "move decal_filter_scale inline, walk decal in 32.32""

This reverts commit dbbd263d77b7888f4d465ad23cbde59944f5972f.

And adds a guard flag for Google3.

Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Change-Id: I6b7615aaf5f161bfad2b3344fd9ab95a7f1e9d47
Reviewed-on: https://skia-review.googlesource.com/c/172944
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
2 files changed