[BlobStorage] Fixing potential overflow

Bug: 779314
Change-Id: I74612639d20544e4c12230569c7b88fbe669ec03
Reviewed-on: https://chromium-review.googlesource.com/747725
Reviewed-by: Victor Costan <pwnall@chromium.org>
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512977}
std::unique_ptr<BlobDataHandle> BlobStorageContext::AddFinishedBlob(
    const BlobDataBuilder& external_builder) {
  TRACE_EVENT0("Blob", "Context::AddFinishedBlob");
  return BuildBlob(external_builder, TransportAllowedCallback());
}

std::unique_ptr<BlobDataHandle> BlobStorageContext::AddFinishedBlob(
    const BlobDataBuilder& external_builder) {
  TRACE_EVENT0("Blob", "Context::AddFinishedBlob");
  return BuildBlob(external_builder, TransportAllowedCallback());
}
