Store the changed_inputs field in build.trace.

Bug: 323021988
Test: Manual tests
Change-Id: If5e060d13f7935ced28d556ab248f2b1e6bdb61d
diff --git a/ui/status/status.go b/ui/status/status.go
index da78994..52ed56a 100644
--- a/ui/status/status.go
+++ b/ui/status/status.go
@@ -41,6 +41,10 @@
 	// It's optional, but one of either Description or Command should be
 	// set.
 	Command string
+
+	// ChangedInputs is the (optional) list of inputs that have changed
+	// since last time this action was run.
+	ChangedInputs []string
 }
 
 // ActionResult describes the result of running an Action.