[pre_freeze] Add support for telling tasks how they were run

This CL allows us to post tasks with PreFreeze taking a single parameter, telling whether or not they were run directly or via PreFreeze. This will allow us to determine in each task how aggressively to purge the resources, based on how the task was run.

Bug: 325482668, 331432538
Change-Id: I46a5c5b423a290abc96c4ad92afdbd4d05e86414
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5403134


Reviewed-by: Benoit Lize <lizeb@chromium.org>
Commit-Queue: Thiabaud Engelbrecht <thiabaud@google.com>
Cr-Commit-Position: refs/heads/main@{#1283104}