Move session service and supervised users to buildflags.

chrome/browser/sync/supervised_user_signin_manager_wrapper.cc

Index: chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
diff --git a/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc b/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
index 2e197af2e4d0d2c824642c296a89ba10ecb35ad5..c8b7304079f954d2248f769c8a19c30f40ee4e99 100644
--- a/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
+++ b/chrome/browser/sync/supervised_user_signin_manager_wrapper.cc
@@ -5,10 +5,11 @@
 #include "chrome/browser/sync/supervised_user_signin_manager_wrapper.h"
 
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/common/features.h"
 #include "components/signin/core/browser/signin_manager_base.h"
 #include "google_apis/gaia/gaia_constants.h"
 
-#if defined(ENABLE_SUPERVISED_USERS)
+#if BUILDFLAG(ENABLE_SUPERVISED_USERS)
 #include "chrome/browser/supervised_user/supervised_user_constants.h"
 #endif
 
@@ -20,7 +21,7 @@ SupervisedUserSigninManagerWrapper::SupervisedUserSigninManagerWrapper(
 SupervisedUserSigninManagerWrapper::~SupervisedUserSigninManagerWrapper() {}
 
 std::string SupervisedUserSigninManagerWrapper::GetEffectiveUsername() const {
-#if defined(ENABLE_SUPERVISED_USERS)
+#if BUILDFLAG(ENABLE_SUPERVISED_USERS)
   if (profile_->IsLegacySupervised())
     return supervised_users::kSupervisedUserPseudoEmail;
 #endif
@@ -28,7 +29,7 @@ std::string SupervisedUserSigninManagerWrapper::GetEffectiveUsername() const {
 }
 
 std::string SupervisedUserSigninManagerWrapper::GetAccountIdToUse() const {
-#if defined(ENABLE_SUPERVISED_USERS)
+#if BUILDFLAG(ENABLE_SUPERVISED_USERS)
   if (profile_->IsLegacySupervised())
     return supervised_users::kSupervisedUserPseudoEmail;
 #endif
@@ -36,7 +37,7 @@ std::string SupervisedUserSigninManagerWrapper::GetAccountIdToUse() const {
 }
 
 std::string SupervisedUserSigninManagerWrapper::GetSyncScopeToUse() const {
-#if defined(ENABLE_SUPERVISED_USERS)
+#if BUILDFLAG(ENABLE_SUPERVISED_USERS)
   if (profile_->IsLegacySupervised())
     return GaiaConstants::kChromeSyncSupervisedOAuth2Scope;
 #endif