Make cache_dir a raw string.
Make cache_dir a raw string.

R=szager@chromium.org, dnj@chromium.org
BUG=

Review URL: https://codereview.chromium.org/487943003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@291572 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build