Revert "Replace call to lambda with a simple initializer-list."

This reverts commit 8624b8680aa262776813f8a901a1b64689bcbc45.

Reason for revert: Seems to be the cause of presubmit failures: https://ci.chromium.org/ui/p/chromium/builders/ci/linux-presubmit/8673/overview

Original change's description:
> Replace call to lambda with a simple initializer-list.
>
> We are seeing crashed that don't make sense to me in
> GetBasePermissionsPolicyFeatureList. All it does is construct a map.
> It used to operate by constructing a map and calling
> UpdatePermissionsPolicyFeatureListFlagDefaults and that required a
> lambda.
>
> This CL removes the lambda. If nothing else it will simplify the stack
> traces.
>
> Bug: 1492070
> Change-Id: I4dcba0f3c65c7aa7cd3890afd2a717624c288dda
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4941336
> Reviewed-by: Ian Clelland <iclelland@chromium.org>
> Auto-Submit: Fergal Daly <fergal@chromium.org>
> Commit-Queue: Ian Clelland <iclelland@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1210136}

Bug: 1492070
Change-Id: Ia4a1c1687ccf1037b738981e7c617ee265b0771b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4942613
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Takumi Fujimoto <takumif@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1210488}