Update and Clean Up value_cleanup Tool

This change adds a value rewriter to the value_cleanup clang tool. It is
intended to be extended for future use cases, currently it supports the
renaming of base::Value::GetType to base::Value::type.

Furthermore, this change removes the existing ListValueRewriters which
became obsolete with r464866. For future discoverability it adds a
reference to //docs/clang_tool_refactoring.md.

Bug: 646113, 581865
Change-Id: I07b5c1279753a65c123ebdd4a5c5f3a384321081
Reviewed-on: https://chromium-review.googlesource.com/702454
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508932}
12 files changed