Folds the lowbox concept into AppContainer. This will unlock the ability
to add new security capabilities.
This change also renames AppContainerProfile to AppContainer since not all
app containers have profiles.
Validated the renderer process and GPU app containers, which exercise
these code paths, still worked appropriately.
Bug: 1184556
Change-Id: I39d276c6570d716041c463f2468527841572d3cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2734105
Reviewed-by: James Forshaw <forshaw@chromium.org>
Commit-Queue: Emily Andrews <emiled@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#872561}
067107556c