Convert base::test::ParseJson() to return base::Value.

Rename the existing ParseJson() to ParseJsonDeprecated(). Mass update
callers to use ParseJsonDeprecated(), except in
url_request_context_config_unittest.cc, which already has a
std::unique_ptr<base::Value> to base::Value converter wrapper. Remove
the wrapper there.

BUG=932873
TBR=benwells@chromium.org,mef@chromium.org,mfoltz@chromium.org,piman@chromium.org

Change-Id: Iba2dc916b123446f5786b042f76633898174d535
Reviewed-on: https://chromium-review.googlesource.com/c/1476247
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#633632}
34 files changed