Remove unneeded scoped_refptr<>::get on method bind

This CL adds a clang tool to rewrite unneeded scoped_refptr<>::get, and
applies it to //base.

To build and apply this tool, run below:
$ ./tools/clang/scripts/update.py --force-local-build --without-android --tools base_bind_rewriter
$ ./tools/clang/scripts/run_tool.py --regenerate-compdb base_bind_rewriters out/Release base

Review-Url: https://codereview.chromium.org/2283003002
Cr-Commit-Position: refs/heads/master@{#415616}
7 files changed