Revert "Extensions: Remove temporary cleanup code from crbug.com/558299"

This reverts commit fa48bec92e8b0856c65255469407f51db129dfbd.

Reason for revert: The new CHECK() is crashing, so it seems there is more to be cleaned up.  We need to investigate further.

Original change's description:
> Extensions: Remove temporary cleanup code from crbug.com/558299
> 
> In the past, there was a bug where some themes incorrectly got synced
> into the EXTENSIONS data type, so we added cleanup code to remove the
> bad data. That was long ago and all bad data should be long gone now,
> so let's get rid of the cleanup code.
> 
> Bug: none
> Change-Id: I53fcc8ecb208e9fce6565cda70ec57cc960f9b6c
> Reviewed-on: https://chromium-review.googlesource.com/1124680
> Reviewed-by: Devlin <[email protected]>
> Commit-Queue: Marc Treib <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#572255}

[email protected],[email protected]

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: none
Change-Id: If10997927100f17c505eb83221770c47e4e04b7e
Reviewed-on: https://chromium-review.googlesource.com/1136614
Reviewed-by: Devlin <[email protected]>
Commit-Queue: Devlin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#574979}
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 781da8e..ef74a66 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -1398,6 +1398,10 @@
       pending_extension_manager()->GetById(id);
   if (pending_extension_info) {
     if (!pending_extension_info->ShouldAllowInstall(extension)) {
+      // Hack for crbug.com/558299, see comment on DeleteThemeDoNotUse.
+      if (extension->is_theme() && pending_extension_info->is_from_sync())
+        ExtensionSyncService::Get(profile_)->DeleteThemeDoNotUse(*extension);
+
       pending_extension_manager()->Remove(id);
 
       LOG(WARNING) << "ShouldAllowInstall() returned false for " << id