Remove CreateRenderFrameFlags enum.

The CreateRenderFrameFlags enum currently has only one value, which can
easily be replaced by a boolean. This CL is removing this enum in favor
of a bool value.

BUG=357747
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_site_isolation

Review URL: https://codereview.chromium.org/1833243002

Cr-Commit-Position: refs/heads/master@{#383401}
8 files changed