Copy base::JSONReader::Read() to ReadDeprecated().

This is a temporary state to help migrate base::JSONReader::Read() to
return base::Optional<base::Value>. Once most callers have been migrated
to ReadDeprecated(), we can convert Read() to return
base::Optional<base::Value> instead of std::unique_ptr<base::Value>.

Mass migrate chrome/ to ReadDeprecated() here.

Do the same for ReadAndReturnError().

BUG=925165

Change-Id: I7c4dd52f5b0c3ff20a7e69558b4b94e114bd430f
Reviewed-on: https://chromium-review.googlesource.com/c/1435715
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631876}
134 files changed