crash-reporter: Change layout for the container directory of procfs files.

This CL modifies UserCollector to copy procfs files of a crashed process
into /tmp/crash_reporter/<pid> instead of /tmp/crash_reporter.<pid>.
The new directory layout makes it easier for autotest to archive
leftover files under /tmp/crash_reporter due to core2md failures.

BUG=chromium-os:24646
TEST=Tested the following:
1. Build crash-reporter and run unit tests.
2. Run the following autotest tests on a Cr48:
   - logging_CrashSender
   - logging_UserCrash

Change-Id: I435374eabc1574216881318ddacdfa9d1648c875
Reviewed-on: https://gerrit.chromium.org/gerrit/13697
Commit-Ready: Ben Chan <[email protected]>
Reviewed-by: Ben Chan <[email protected]>
Tested-by: Ben Chan <[email protected]>
1 file changed