[base] Replace Contains{Key,Value} with Contains in //remoting

This change replaces usages of base::ContainsKey() and base::ContainsValue()
with base::Contains() in //remoting.

Reproduction:
 - sed -i 's/\bbase::ContainsKey\b/base::Contains/g'
 - sed -i 's/\bbase::ContainsValue\b/base::Contains/g'
 - git cl format

This CL was uploaded by git cl split.

R=yuweih@chromium.org

Bug: 970209
Change-Id: Ia9806b137c248375d00a1756ab44f06ce18bb275
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648173
Auto-Submit: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Yuwei Huang <yuweih@chromium.org>
Commit-Queue: Yuwei Huang <yuweih@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666821}