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Add functions which support validating and parsing the
JSON matching pattern configuration string into a format
supported by |PatternProvider|. Also provide support for
versioning and replacing the configuration in
|PatternProvider|. Due to the nature of the change,
|PatternProvider| was changed to support testing with a
synchronously loaded configuration.

Change-Id: I662ecb933a4067c0ee6d188defe5e982b85469a7
Bug: 1121990
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359990Reviewed-by: Matthias Körber <koerber@google.com>
Reviewed-by: Christoph Schwering <schwering@google.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Martynas Sinkievič <marsin@google.com>
Cr-Commit-Position: refs/heads/master@{#813097}