Add a new reboot reason.

The new reboot reason is "UTILITY_PROCESS_CRASH". It's used when the
utility process is in a crash loop.

Bug: internal b/166313191
Test: None.
Change-Id: I62e0ac9280505172ad1b0461f18075d70eed2bfd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2376450Reviewed-by: Luke Halliwell (slow) <halliwell@chromium.org>
Commit-Queue: Guohui Deng <guohuideng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801613}

chromecast/public/reboot_shlib.h

@@ -75,6 +75,10 @@ class CHROMECAST_EXPORT RebootShlib {
 
     // A reboot is triggered due to successive OOM events.
     REPEATED_OOM = 13,
+
+    // A reboot is triggered when the utility process is found to be in
+    // crash loop.
+    UTILITY_PROCESS_CRASH = 14,
   };
 
   // Initializes any platform-specific reboot systems.