Rename class LinuxSandbox to SandboxLinux

This is for consistency with classes SandboxWin and SandboxMac.

Also rename
  services/service_manager/public/cpp/standalone_service/linux_sandbox.h
  services/service_manager/public/cpp/standalone_service/linux_sandbox.cc
to match the convention. These are files duplicated from content that will
become obsolete once the real content files are moved to service manager.

Bug: 708738
Change-Id: I4a376c8e1d63987bc298df4c0b0a3dccb4301b2f
Reviewed-on: https://chromium-review.googlesource.com/734323
Reviewed-by: Mark Seaborn <mseaborn@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#511265}
16 files changed