[GCPW] Fix invalid GCPW association information not being cleaned.

The function FindUserBySID was not returning a successful result
when it is passed no username or domain to fill even though the
user was found.

Bug: 933850
Change-Id: I97c9e208ea85695b94651029aac4c58b551beaa6
Reviewed-on: https://chromium-review.googlesource.com/c/1479091
Auto-Submit: Tien Mai <tienmai@chromium.org>
Commit-Queue: Roger Tawa <rogerta@chromium.org>
Reviewed-by: Roger Tawa <rogerta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#633834}

chrome/credential_provider/gaiacp/os_user_manager.cc

@@ -422,9 +422,9 @@ HRESULT OSUserManager::FindUserBySID(const wchar_t* sid,
                           local_domain_buffer, &domain_length, &use)) {
     hr = HRESULT_FROM_WIN32(::GetLastError());
     if (hr != HRESULT_FROM_WIN32(ERROR_NONE_MAPPED)) {
-      if (hr == HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER)) {
-        if ((username_size > 0 && name_length >= username_size))
-          hr = S_OK;
+      if (username_size == 0 &&
+          hr == HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER)) {
+        hr = S_OK;
       }
     }
   }