555f70f3a2
Putting thumbnail-related definitions in thumbnail.h. This does require an extra forward declaration of `Thumbnail` in thumbnail.h to work. Change-Id: If948e4dbdc1fa8051c2d05e40e98381b45a7fe29 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5714694 Reviewed-by: Alan Screen <awscreen@chromium.org> Commit-Queue: Lei Zhang <thestig@chromium.org> Cr-Commit-Position: refs/heads/main@{#1329839}