Reland "[s13n] Migrate ContentAreaAccountsMigration away from GCMS::Observer"

This reverts commit 71359b31.

Reason for revert: message from the sheriff that reverted it [1]:

"
Well, theoretically there still could have been an interaction of
your CL with another one that would have caused the failing test to 
change from ActivityKeptInPref to SupervisedUserRemoved.

That said, the MSan build with my revert just finished and it's 
indeed still red. So your CL likely indeed wasn't the culprit.

Sorry for that. Please go ahead and reland.
"

[1] https://bugs.chromium.org/p/chromium/issues/detail?id=926154#c10
Original change's description:
> Revert "[s13n] Migrate ContentAreaAccountsMigration away from GCMS::Observer"
> 
> This reverts commit 5f7f5569.
> 
> Reason for revert: Seems to break multiple Chrome OS trybots. See crbug.com/926154 for more details.
> 
> Original change's description:
> > [s13n] Migrate ContentAreaAccountsMigration away from GCMS::Observer
> > 
> > CL changes the inheritance ofi ContentAreaAccountsMigration from
> > GaiaCookieManagerService::Observer to IdentityManager::Observer instead.
> > 
> > No functionality change expected.
> > 
> > BUG=859882
> > 
> > Change-Id: I907b2624d23e93b6a0ecbcda3e39f0322f238612
> > Reviewed-on: https://chromium-review.googlesource.com/c/1436916
> > Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
> > Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> > Reviewed-by: Lowell Manners <lowell@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#626748}
> 
> TBR=xiyuan@chromium.org,tonikitoo@igalia.com,lowell@chromium.org
> 
> Change-Id: Ide04520a6a6f249e5220a6b9086c80b591bc923e
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: 859882,926154
> Reviewed-on: https://chromium-review.googlesource.com/c/1442197
> Reviewed-by: Martin Šrámek <msramek@chromium.org>
> Commit-Queue: Martin Šrámek <msramek@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#626972}

TBR=xiyuan@chromium.org,msramek@chromium.org,tonikitoo@igalia.com,lowell@chromium.org

Change-Id: I565d0335169be1e4fb61954f0d2f1a3dc8319cc7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 859882, 926154
Reviewed-on: https://chromium-review.googlesource.com/c/1443231Reviewed-by: Antonio Gomes <tonikitoo@igalia.com>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#627010}

chrome/browser/chromeos/account_manager/account_manager_migrator.cc

@@ -28,7 +28,6 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/account_reconcilor_factory.h"
 #include "chrome/browser/signin/account_tracker_service_factory.h"
-#include "chrome/browser/signin/gaia_cookie_manager_service_factory.h"
 #include "chrome/browser/signin/identity_manager_factory.h"
 #include "chrome/browser/web_data_service_factory.h"
 #include "chrome/common/pref_names.h"
@@ -40,9 +39,9 @@
 #include "components/prefs/pref_service.h"
 #include "components/signin/core/browser/account_reconcilor.h"
 #include "components/signin/core/browser/account_tracker_service.h"
-#include "components/signin/core/browser/gaia_cookie_manager_service.h"
 #include "components/signin/core/browser/webdata/token_web_data.h"
 #include "components/webdata/common/web_data_service_consumer.h"
+#include "services/identity/public/cpp/accounts_in_cookie_jar_info.h"
 #include "services/identity/public/cpp/identity_manager.h"
 
 namespace chromeos {
@@ -273,39 +272,34 @@ class DeviceAccountMigration : public AccountMigrationBaseStep,
 // to |AccountManager|. The objective is to migrate the account names only. We
 // cannot migrate any credentials (cookies).
 class ContentAreaAccountsMigration : public AccountMigrationBaseStep,
-                                     GaiaCookieManagerService::Observer {
+                                     identity::IdentityManager::Observer {
  public:
-  ContentAreaAccountsMigration(
-      AccountManager* account_manager,
-      identity::IdentityManager* identity_manager,
-      GaiaCookieManagerService* gaia_cookie_manager_service)
+  ContentAreaAccountsMigration(AccountManager* account_manager,
+                               identity::IdentityManager* identity_manager)
       : AccountMigrationBaseStep(kContentAreaAccountsMigration,
                                  account_manager,
                                  identity_manager),
-        gaia_cookie_manager_service_(gaia_cookie_manager_service) {}
+        identity_manager_(identity_manager) {}
   ~ContentAreaAccountsMigration() override {
-    gaia_cookie_manager_service_->RemoveObserver(this);
+    identity_manager_->RemoveObserver(this);
   }
 
  private:
   void StartMigration() override {
     DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
-    std::vector<gaia::ListedAccount> signed_in_content_area_accounts;
-    std::vector<gaia::ListedAccount> signed_out_content_area_accounts;
-    gaia_cookie_manager_service_->AddObserver(this);
-    if (gaia_cookie_manager_service_->ListAccounts(
-            &signed_in_content_area_accounts,
-            &signed_out_content_area_accounts)) {
-      OnGaiaAccountsInCookieUpdated(
-          signed_in_content_area_accounts, signed_out_content_area_accounts,
+    identity_manager_->AddObserver(this);
+    identity::AccountsInCookieJarInfo accounts_in_cookie_jar_info =
+        identity_manager_->GetAccountsInCookieJar();
+    if (accounts_in_cookie_jar_info.accounts_are_fresh) {
+      OnAccountsInCookieUpdated(
+          accounts_in_cookie_jar_info,
           GoogleServiceAuthError(GoogleServiceAuthError::NONE));
     }
   }
 
-  void OnGaiaAccountsInCookieUpdated(
-      const std::vector<gaia::ListedAccount>& signed_in_content_area_accounts,
-      const std::vector<gaia::ListedAccount>& signed_out_content_area_accounts,
+  void OnAccountsInCookieUpdated(
+      const identity::AccountsInCookieJarInfo& accounts_in_cookie_jar_info,
       const GoogleServiceAuthError& error) override {
     DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
     // We should not have reached here without |OnGetAccounts| having been
@@ -313,10 +307,10 @@ class ContentAreaAccountsMigration : public AccountMigrationBaseStep,
     // Furthermore, Account Manager must have been populated with the Device
     // Account before this |Step| is run.
     DCHECK(!IsAccountManagerEmpty());
-    gaia_cookie_manager_service_->RemoveObserver(this);
+    identity_manager_->RemoveObserver(this);
 
-    MigrateAccounts(signed_in_content_area_accounts,
-                    signed_out_content_area_accounts);
+    MigrateAccounts(accounts_in_cookie_jar_info.signed_in_accounts,
+                    accounts_in_cookie_jar_info.signed_out_accounts);
 
     FinishWithSuccess();
   }
@@ -334,8 +328,8 @@ class ContentAreaAccountsMigration : public AccountMigrationBaseStep,
     }
   }
 
-  // A non-owning pointer to |GaiaCookieManagerService|.
-  GaiaCookieManagerService* const gaia_cookie_manager_service_;
+  // A non-owning pointer to |IdentityManager|.
+  identity::IdentityManager* const identity_manager_;
 
   SEQUENCE_CHECKER(sequence_checker_);
 
@@ -524,9 +518,7 @@ void AccountManagerMigrator::AddMigrationSteps() {
       WebDataServiceFactory::GetTokenWebDataForProfile(
           profile_, ServiceAccessType::EXPLICIT_ACCESS) /* token_web_data */));
   migration_runner_.AddStep(std::make_unique<ContentAreaAccountsMigration>(
-      account_manager, identity_manager,
-      GaiaCookieManagerServiceFactory::GetForProfile(
-          profile_) /* gaia_cookie_manager_service */));
+      account_manager, identity_manager));
 
   if (arc::IsArcProvisioned(profile_)) {
     // Add a migration step for ARC only if ARC has been provisioned. If ARC has
@@ -610,7 +602,7 @@ AccountManagerMigratorFactory::AccountManagerMigratorFactory()
   // be re-enabled once migration is done.
   DependsOn(AccountReconcilorFactory::GetInstance());
   // For getting Chrome content area accounts.
-  DependsOn(GaiaCookieManagerServiceFactory::GetInstance());
+  DependsOn(IdentityManagerFactory::GetInstance());
 }
 
 AccountManagerMigratorFactory::~AccountManagerMigratorFactory() = default;