[BlobAsync] Patch 4: Browser Classes & Logic.
This patch encompasses all browser classes and logic for blob async transportation. This is a no-op.

Patches:
1: https://codereview.chromium.org/1287303002 (committed)
2: https://codereview.chromium.org/1288373002 (committed)
3: https://codereview.chromium.org/1292523002 (committed)
4: https://codereview.chromium.org/1098853003
Hookup: https://codereview.chromium.org/1234813004

See https://bit.ly/BlobStorageRefactor

BUG=375297

Review URL: https://codereview.chromium.org/1098853003

Cr-Commit-Position: refs/heads/master@{#362802}
14 files changed