The sysroot are generally useful (for example when
cross compiling) and not limited to use in the installer
or official releases.
Another reason to move this is that it would allow other
projects to more easily share chromium's build setup
without depending on chrome/.
Also, rename the install script to simply install-sysroot.
This way the script can keep the same name and support
multiple different debian releases without needing
to duplicate the script (e.g. when we switch to jessie).
BUG=504446
TEST=cross build chromium for arm and ia32
Review URL: https://codereview.chromium.org/1141003002
Cr-Original-Commit-Position: refs/heads/master@{#336843}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 8208b4d81396c11e1f8ca8f6ffe52b9fcea87d05
sbc