title: chrome.storage.local.get causes exception
body: <p>I'm trying to save pair pageUrl:imageUrl into chrom local storage. Here is the code:   </p>
  
  <pre><code>    function saveImage (href, urlImage)
      {
          var dataObj = {href:urlImage};
          dataObj[href] = urlImage;
          chrome.storage.local.set(dataObj);
          console.log("Image url has been saved into storage "+href);
  
      }
  
      function tryLoadCachedImageUrl(hrefObj)
      {
          console.log("Trying to load image from storage: "+hrefObj.href);
          chrome.storage.local.get(hrefObj.href, 
          function(result){   
                  loadImages(result,hrefObj);
          });
  
      }
  </code></pre>
  
  <p>chrome.storage.local.get causes exception:</p>
  
  <blockquote>
    <p>Error in response to storage.get: ReferenceError: obj is not defined</p>
  </blockquote>
  
  <p>hrefObj.href contains string, equal to <code>pageUrl</code> which was saved in <code>saveImage</code></p>
  
  <p>What am I doing wrong?</p>