Add comments to base/values.h about refactoring.

This clarifies what is being changed and what the old and new code looks like.

Change-Id: Ic8f78896a0d9b607c29f9ffc3af49ea5c678db2d
Reviewed-on: https://chromium-review.googlesource.com/646832
Reviewed-by: Jan Wilken Dörrie <[email protected]>
Cr-Commit-Position: refs/heads/master@{#499271}
1 file changed