AppCache: Remove unreachable code in AppCacheQuotaClient.

The QuotaClient interface now guarantees that clients only get called
with StorageTypes that they were registered for. In particular,
AppCacheQuotaClient is only called with kTemporary. This precondition
has been covered by a DCHECK for a while.

This CL removes a check that cannot be true under the current
QuotaClient interface.

Change-Id: I2057935df768f657f13a7f4297864ab62cc7ce1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500767
Commit-Queue: Victor Costan <pwnall@chromium.org>
Commit-Queue: enne <enne@chromium.org>
Auto-Submit: Victor Costan <pwnall@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821039}

content/browser/appcache/appcache_quota_client.cc

@@ -151,11 +151,6 @@ void AppCacheQuotaClient::DeleteOriginData(const url::Origin& origin,
   }
 
   current_delete_request_callback_ = std::move(callback);
-  if (type != StorageType::kTemporary) {
-    DidDeleteAppCachesForOrigin(net::OK);
-    return;
-  }
-
   GetUIThreadTaskRunner({})->PostTask(
       FROM_HERE,
       base::BindOnce(&AppCacheServiceImpl::DeleteAppCachesForOrigin, service_,