metrics: add HwWatchdogReboot to CrosEvents

Add HwWatchdogReboot to CrosEvents support.

BUG=chromium:221000
TEST=none

Change-Id: I7388c6d1ee93a73f930d591552b18ea7bba7743f
Signed-off-by: Grant Grundler <grundler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/46593
Reviewed-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
diff --git a/metrics/metrics_library.cc b/metrics/metrics_library.cc
index a2227ac..075176f 100644
--- a/metrics/metrics_library.cc
+++ b/metrics/metrics_library.cc
@@ -319,6 +319,8 @@
    */
   if (event.compare("ModemManagerCommandSendFailure") == 0) {
     n = 0;
+  } else if (event.compare("HwWatchdogReboot") == 0) {
+    n = 1;
   } else {
     return false;
   }