Revert "Add Flag to build with prebuilt chromium"

This reverts commit a5f5addc7a1d8112f008a12970cd14bccb3bc77a.

Change-Id: Iec56272522ba5a1409e5e8a8098c413d83ebc46a
Merge "Revert "Add Flag to build with prebuilt chromium"" into kitkat