I gather you haven't done much jQuery coding. That's equivalent to:

  $("html div.title img.icon").attr("src")

The last .attr("src") is purely because jQuery always deals with a node / a collection of nodes.

You can also do arbitrary attribute searches:

  $("html div[class~='title'] img[src*='google']")
  // "~=" == "contains word" - space-delimited to match html classes
  // "*=" == "contains substring"

http://api.jquery.com/category/selectors/