Initialize Chromoting env from /etc/default/locale and per-user file.
Initialize Chromoting env from /etc/default/locale and per-user file.

A PAM-authenticated session normally gets the environment from
several files. Chromoting currently only reads /etc/environment, so this
CL expands it to read /etc/default/locale and ~/.pam_environment as well.

BUG=431325

Review URL: https://codereview.chromium.org/1432153003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#359883}

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