QUIC - Always pesist 1000 MRU alternate protocols to preferences file.
Deleted the experiment to load either 200 or 1000 servers from disk.
+ Obsoleted the following histograms
++ Net.AlternateProtocolUsage.200Truncated
++ Net.AlternateProtocolUsage.1000Truncated
Reverted the changes related to the above from the following CL:
https://codereview.chromium.org/
298683010/
R=jar@chromium.org, rch@chromium.org
Review URL: https://codereview.chromium.org/
675783005
Cr-Commit-Position: refs/heads/master@{#301070}