GitLab

Removed the 'using namespace std' directive from the header with using qualified
name for string as std::string.

TBR=brettw@chromium.org

Review URL: https://codereview.chromium.org/441083003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287758 0039d316-1c4b-4281-b951-d872f2087c98