Convert assistant_optin_utils.cc to IdentityManager

It was using SigninManagerBase API to get the primary (authenticated)
account id. It's now using the IdentityManager API.

Bug: 890806
Change-Id: I2902cd16c4040301f84d238dc46ca2b8f9e10793
Reviewed-on: https://chromium-review.googlesource.com/c/1276609
Commit-Queue: Sergio Villar <svillar@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600058}

chrome/browser/ui/webui/chromeos/assistant_optin/assistant_optin_utils.cc

@@ -6,7 +6,7 @@
 
 #include "base/metrics/histogram_macros.h"
 #include "chrome/browser/consent_auditor/consent_auditor_factory.h"
-#include "chrome/browser/signin/signin_manager_factory.h"
+#include "chrome/browser/signin/identity_manager_factory.h"
 #include "chrome/browser/ui/webui/chromeos/user_image_source.h"
 #include "chrome/grit/browser_resources.h"
 #include "chrome/grit/generated_resources.h"
@@ -14,6 +14,7 @@
 #include "components/consent_auditor/consent_auditor.h"
 #include "components/signin/core/browser/signin_manager_base.h"
 #include "components/user_manager/user_manager.h"
+#include "services/identity/public/cpp/identity_manager.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/webui/web_ui_util.h"
 
@@ -208,10 +209,9 @@ using sync_pb::UserConsentTypes;
 void RecordActivityControlConsent(Profile* profile,
                                   std::string ui_audit_key,
                                   bool opted_in) {
-  SigninManagerBase* signin_manager =
-      SigninManagerFactory::GetForProfile(profile);
-  DCHECK(signin_manager->IsAuthenticated());
-  std::string account_id = signin_manager->GetAuthenticatedAccountId();
+  auto* identity_manager = IdentityManagerFactory::GetForProfile(profile);
+  DCHECK(identity_manager->HasPrimaryAccount());
+  const std::string account_id = identity_manager->GetPrimaryAccountId();
 
   UserConsentTypes::AssistantActivityControlConsent consent;
   consent.set_ui_audit_key(ui_audit_key);