The Linux sandbox overrides localtime to use a synchronous IPC to the browser process.
https://cs.chromium.org/chromium/src/content/zygote/zygote_main_linux.cc?q=localtime_override&sq=package:chromium&l=263

This was added to allow renderers to correctly do time conversions.
"""
    73fa6399bd9198863d7d9e01db6fcc8cdfcc8837
...
    Linux sandbox: plumb timezone calls through the sandbox
    
    The localtime (and localtime_r) functions try to access /etc/localtime
    in the filesystem. For sandboxed renderers, this fails, the the
    functions default to a UTC timezone.

    These functions are called from within WebCore and V8 and there's no
    clean way to patch the source code in place to do a hairpin turn and
    manage an IPC. Additionally, we cannot overwrite the calls with the
    usual symbol resolution procedures since the same chrome binary must
    serve as both the unsandboxed browser and sandboxed renderer.

"""

For Out of Process Heap Profiling, we spawn a profiling service in a sandboxed utility process. The browser process synchronously writes to an OS pipe [potentially blocking], which the profiling service needs to regularly read from. This currently can cause a deadlock, since the reader thread of the profiling service has LOG statements, which call localtime, which in turn attempts synchronous IPC to the browser process.

I'd like to be able to turn off this localtime*_override functionality and just use UTC for this sandboxed, profiling service. 

If you want more information about the profiling service, please see this preliminary design doc [not ready for review]: https://docs.google.com/document/d/1qBANWBo9_LXtwLa8xm3GBZ0oBwWbGPu0_keVKGunXaQ/edit#

I'm not too familiar with the Linux sandbox. The easiest solution for me to implement would be a global function exposed by the sandbox which turns off the IPC functionality, which can be called post sandbox initialization. I assume it's also possible to do some type of pre-sandbox initialization, but I'd have to do some digging.

Any concerns/objections?