Merge third_party/brotli/src from https://chromium.googlesource.com/external/font-compression-reference.git at 494c85cebbaaa0db345df69ffa1b639aa4652022

This commit was generated by merge_from_chromium.py.

Change-Id: Ib3fbe3e72d8026481ab406195954e0ee382d7816