I figured it out for myself...just took some deep digging through Protractor and Selenium documentation. Here is some example code:

  it('should pan plots when you click and drag', function() {

    var plot0 = element(by.css('.plot > canvas'));

    browser.actions()

      .mouseMove(plot0, {x: 100, y: 100}) // 100px from left, 100 px from top of plot0

      .mouseDown()

      .mouseMove({x: 400, y: 0}) // 400px to the right of current location

      .perform();

  });