From https://plus.google.com/+FrancoisBeaufort/posts/Jr8sPswJ172, "I've never understood why there isn't a checkbox next to "Today" which allows you to delete all of today's browsing history easily. I know this can be done through the dropdown in the Clear Browsing History option, but I'd imagine that people are either checking their history to find what they want or clearing it to get rid of what they don't want seen. Might as well make either option easy."