buffet: Fixed command state spelling for "cancelled"

GCD spec apparently expects the command status to be spelled as
"cancelled". Fixed...

BUG=brillo:552
TEST=`FEATURES=test emerge-link buffet`

Change-Id: I11a848f2f29ca7d63ce95d130b2a84aa75ced7fd
Reviewed-on: https://chromium-review.googlesource.com/260028
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/commands/command_instance.cc b/buffet/commands/command_instance.cc
index 7d54ed7..d39e4a1 100644
--- a/buffet/commands/command_instance.cc
+++ b/buffet/commands/command_instance.cc
@@ -22,7 +22,7 @@
 const char CommandInstance::kStatusPaused[] = "paused";
 const char CommandInstance::kStatusError[] = "error";
 const char CommandInstance::kStatusDone[] = "done";
-const char CommandInstance::kStatusCanceled[] = "canceled";
+const char CommandInstance::kStatusCancelled[] = "cancelled";
 const char CommandInstance::kStatusAborted[] = "aborted";
 const char CommandInstance::kStatusExpired[] = "expired";
 
@@ -182,7 +182,7 @@
 }
 
 void CommandInstance::Cancel() {
-  SetStatus(kStatusCanceled);
+  SetStatus(kStatusCancelled);
   RemoveFromQueue();
   // The command will be destroyed after that, so do not access any members.
 }