Fix memory leak in BlobRegistryImpl

Bug: 954458
Change-Id: I9980361d8b97c6de90d2784b229630cdabfbf0cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1575055
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652802}
6 files changed