title: save image from webpage without requiring server to still have the image
body: <p>I often load images in new tabs and sometimes leave them there overnight. Despite the image being fully loaded in its tab, when I go to save, chrome informs me there is "no file", which presumably means it is no longer found at that address on the server, and refuses to save. I assume the file has also fallen out of chrome's cache.</p>
  
  <ol>
  <li><p>Is there reason chrome doesn't remember a tiny bit of metadata and regenerate the image from the view if it can't fetch it from the server or cache? Because it's kinda really frustrating to not be able to save something that's right there.</p></li>
  <li><p>Starting from an unmodified page, without preparation, how could javascript (through an extension if needed) be used to save an image under these conditions?</p></li>
  </ol>
  
  <p>Failing that, a somewhat annoying solution is to have an extension that saves the image temporarily on tab load, and then monitors downloads so it can serve the saved images when appropriate.</p>