arc: Add the --arc-available switch

chromeos/chromeos_switches.cc

Index: chromeos/chromeos_switches.cc
diff --git a/chromeos/chromeos_switches.cc b/chromeos/chromeos_switches.cc
index bccec7f0ff4d88abc0bb0a793dcf246829fb80b6..1fb966c4e6f8d524949a1c0e0c50737b26ce0bc1 100644
--- a/chromeos/chromeos_switches.cc
+++ b/chromeos/chromeos_switches.cc
@@ -58,6 +58,9 @@ const char kAllowRAInDevMode[] = "allow-ra-in-dev-mode";
 // Path for app's OEM manifest file.
 const char kAppOemManifestFile[] = "app-mode-oem-manifest";
 
+// Signals the availability of the ARC instance on this device.
+const char kArcAvailable[] = "arc-available";
+
 // Screenshot testing: specifies the directoru where artifacts will be stored.
 const char kArtifactsDir[] = "artifacts-dir";