debugd: collect cr50 version

Let's grab the version info that cr50's usb_updater leaves in /var/cache.

Signed-off-by: Benson Leung <bleung@chromium.org>

BUG=chrome-os-partner:61301
TEST=reboot system. Check that "cr50_version" appears in chrome://system
CQ-DEPEND=CL:431504

Reviewed-on: https://chromium-review.googlesource.com/431264
Commit-Ready: Benson Leung <bleung@chromium.org>
Tested-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
(cherry picked from commit 1526c8f9a7d89515ac853fe5ffdd2387f7728c2b)

Change-Id: I3ab334a00dc9d153a0fa97e31f1a10bb6abe6f89
Reviewed-on: https://chromium-review.googlesource.com/431546
Commit-Queue: Benson Leung <bleung@chromium.org>
Tested-by: Benson Leung <bleung@chromium.org>
Trybot-Ready: Benson Leung <bleung@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
diff --git a/debugd/src/log_tool.cc b/debugd/src/log_tool.cc
index b2dd7e5..be24108 100644
--- a/debugd/src/log_tool.cc
+++ b/debugd/src/log_tool.cc
@@ -62,6 +62,7 @@
   { "console-ramoops", "/bin/cat /dev/pstore/console-ramoops 2> /dev/null" },
   { "cpu", "/usr/bin/uname -p" },
   { "cpuinfo", "/bin/cat /proc/cpuinfo" },
+  { "cr50_version", "/bin/cat /var/cache/cr50-version" },
   { "cros_ec",
     "/bin/cat /var/log/cros_ec.previous /var/log/cros_ec.log 2> /dev/null" },
   { "cros_ec_panicinfo",