Use install_static::GetAppGuid instead of the hardcoded string in BrandcodeConfigFetcher.

Bug: 769756
Change-Id: Ifdcb0a5145ffad1d563562e2b2ea2390ff074cdc
Reviewed-on: https://chromium-review.googlesource.com/1213178
Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590275}
void XmlConfigParser::EndElementImpl(void* ctx, const xmlChar* name) {
  XmlConfigParser* context = FromContext(ctx);
  context->elements_.pop_back();
}

void XmlConfigParser::EndElementImpl(void* ctx, const xmlChar* name) {
  XmlConfigParser* context = FromContext(ctx);
  context->elements_.pop_back();
}
