Move cairo image generation out of the Canvas WTP generator main loop
This will be useful in follow-up CL, where more logic will be added in
the new _genereate_cairo_images function.
Bug: 364549423
Change-Id: I786821433ea553cb51a18d80388fa1c1699419cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5836916
Commit-Queue: Jean-Philippe Gravel jpgravel@chromium.org
Reviewed-by: Andres Ricardo Perez andresrperez@chromium.org
Cr-Commit-Position: refs/heads/main@{#1353354}