Remove kNeedArcMigrationPolicyCheck which is unused

BUG=None
TEST=try

Change-Id: Ia7fe05b5c8f5038edc1d2f41a93d1ebd5c3b23ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2632392Reviewed-by: Igor <igorcov@chromium.org>
Commit-Queue: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844716}

chromeos/constants/chromeos_switches.cc

@@ -459,12 +459,6 @@ const char kMarketingOptInUrl[] = "marketing-opt-in-url";
 // Enables natural scroll by default.
 const char kNaturalScrollDefault[] = "enable-natural-scroll-default";
 
-// If present, the device needs to check the policy to see if the migration to
-// ext4 for ARC is allowed. It should be present only on devices that have been
-// initially issued with ecrypfs encryption and have ARC (N+) available. For the
-// devices in other categories this flag must be missing.
-const char kNeedArcMigrationPolicyCheck[] = "need-arc-migration-policy-check";
-
 // An optional comma-separated list of IDs of apps that can be used to take
 // notes. If unset, a hardcoded list is used instead.
 const char kNoteTakingAppIds[] = "note-taking-app-ids";

chromeos/constants/chromeos_switches.h

@@ -173,8 +173,6 @@ COMPONENT_EXPORT(CHROMEOS_CONSTANTS) extern const char kLoginProfile[];
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS) extern const char kLoginUser[];
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS) extern const char kMarketingOptInUrl[];
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS) extern const char kNaturalScrollDefault[];
-COMPONENT_EXPORT(CHROMEOS_CONSTANTS)
-extern const char kNeedArcMigrationPolicyCheck[];
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS) extern const char kNoteTakingAppIds[];
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS) extern const char kOobeEulaUrlForTests[];
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS)