This directory serves as a home for minimal polyfill of some common APIs within Chromium, //base in particular. This allows the ipcz implementation to depend on a small subset of the Chromium tree when building against Chromium, but to still build and behave as expected when used as a standalone library.
Currently only a subset of logging macros, and stack trace symbolization are polyfilled here. Internal ipcz code which includes util/log.h will get Chromium's base/logging.h definitions when building as part of Chromium; when building standalone, this will instead include standalone/base/logging.h.
Similarly, inclusion of util/stack_trace.h exposes the ipcz::StackTrace type. For Chromium builds this is merely an alias for base::debug::StackTrace in base/debug/stack_trace.h. In standalone builds, the implementation comes from standalone/base/ and is built around Abseil's stack tracing and symbolization.
Any additional polyfill in this directory should be added sparingly and with careful consideration of maintenance costs, since the vast majority of the Chromium tree does not expose stable APIs. Log macros, for example, have been extremely consistent over the lifetime of the Chromium project and are likely to to remain that way, so they're a reasonably good fit here.