ProfileSyncService: Only call ClearPrimaryAccount if there is one

ClearPrimaryAccount is somewhat misnamed: It doesn't actually remove the
account, it only clears the sync-consented bit, so the account will
change from ConsentLevel::kSync to ConsentLevel::kNotRequired.

If the primary account doesn't have sync consent to begin with (i.e.
it's a Sync-the-transport user), then ClearPrimaryAccount should be a
no-op. However, currently it still records metrics, and it notifies
identity observers (even though nothing actually changed).

This CL is a quick-fix for that issue, until ClearPrimaryAccount is
actually fixed/redesigned.

Bug: 1155042
Change-Id: Icc711cbd8eb118fd3d1b2ff28b2f74df4d8cde65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2566947
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833205}

components/sync/driver/profile_sync_service.cc

@@ -1045,13 +1045,18 @@ void ProfileSyncService::OnActionableError(const SyncProtocolError& error) {
       // the next browser startup.
       StopAndClear();
 #if !BUILDFLAG(IS_CHROMEOS_ASH)
-      // On every platform except ChromeOS, sign out the user after a dashboard
-      // clear.
-      if (!IsLocalSyncEnabled()) {
+      // On every platform except ChromeOS, revoke the Sync consent in
+      // IdentityManager after a dashboard clear.
+      if (!IsLocalSyncEnabled() &&
+          identity_manager_->HasPrimaryAccount(signin::ConsentLevel::kSync)) {
         auto* account_mutator = identity_manager_->GetPrimaryAccountMutator();
-
         // GetPrimaryAccountMutator() returns nullptr on ChromeOS only.
         DCHECK(account_mutator);
+
+        // Note that this method is misnamed: It will not actually remove the
+        // primary account, it will just clear the Sync consent bit (i.e. the
+        // account will change from ConsentLevel::kSync to
+        // ConsentLevel::kNotRequired)
         account_mutator->ClearPrimaryAccount(
             signin::PrimaryAccountMutator::ClearAccountsAction::kDefault,
             signin_metrics::SERVER_FORCED_DISABLE,