[iOS][Enterprise] Skips old FRE when SyncDisabled is On

This CL skips the sign in flow of the old FRE when SyncDisabled policy
is On.

(cherry picked from commit ff0ce8a)

Bug: 1257951
Change-Id: I980ec501805793e5dbe95da53218f0aecd9a8dfd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3211707
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Ewann Pellé <ewannpv@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#929663}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3216688
Cr-Commit-Position: refs/branch-heads/4664@{#17}
Cr-Branched-From: 24dc4ee-refs/heads/main@{#929512}

ios/chrome/browser/ui/first_run/BUILD.gn

@@ -66,6 +66,7 @@ source_set("first_run") {
     "//ios/chrome/browser/geolocation",
     "//ios/chrome/browser/main",
     "//ios/chrome/browser/signin",
+    "//ios/chrome/browser/sync",
     "//ios/chrome/browser/ui:feature_flags",
     "//ios/chrome/browser/ui/authentication",
     "//ios/chrome/browser/ui/authentication/signin",

ios/chrome/browser/ui/first_run/welcome_to_chrome_view_controller.mm

@@ -15,6 +15,7 @@
 #include "components/metrics/metrics_pref_names.h"
 #include "components/metrics/metrics_reporting_default_state.h"
 #include "components/prefs/pref_service.h"
+#include "components/sync/driver/sync_service.h"
 #include "components/web_resource/web_resource_pref_names.h"
 #include "ios/chrome/browser/application_context.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
@@ -23,6 +24,8 @@
 #include "ios/chrome/browser/main/browser.h"
 #import "ios/chrome/browser/signin/chrome_account_manager_service.h"
 #import "ios/chrome/browser/signin/chrome_account_manager_service_factory.h"
+#include "ios/chrome/browser/sync/sync_service_factory.h"
+#include "ios/chrome/browser/sync/sync_setup_service.h"
 #import "ios/chrome/browser/ui/authentication/signin/signin_constants.h"
 #import "ios/chrome/browser/ui/authentication/signin/signin_coordinator.h"
 #import "ios/chrome/browser/ui/authentication/signin/signin_utils.h"
@@ -228,8 +231,15 @@ - (void)welcomeToChromeViewDidTapOKButton:(WelcomeToChromeView*)view {
           self.mainBrowser->GetBrowserState());
   self.firstRunConfig.hasSSOAccount = accountManagerService->HasIdentities();
 
-  if (!signin::IsSigninAllowedByPolicy()) {
-    // Sign-in is disabled by policy. Skip the sign-in flow.
+  syncer::SyncService* syncService = SyncServiceFactory::GetForBrowserState(
+      self.mainBrowser->GetBrowserState());
+  BOOL shouldSkipSignInFlow =
+      syncService->GetDisableReasons().Has(
+          syncer::SyncService::DISABLE_REASON_ENTERPRISE_POLICY) ||
+      !signin::IsSigninAllowedByPolicy();
+
+  if (shouldSkipSignInFlow) {
+    // Sign-in or sync is disabled by policy. Skip the sign-in flow.
     self.firstRunConfig.signInAttemptStatus =
         first_run::SignInAttemptStatus::SKIPPED_BY_POLICY;
     SigninCompletionInfo* completionInfo =