Do Chrome extensions have access to local storage?

Even simpler than that:

To read:

    var myStoredValue = localStorage["TheKeyToMyStoredValue"];

To write:

    localStorage["TheKeyToMyStoredValue"] = myNewValueToStore;

To get rid of:

    delete localStorage["TheKeyToMyStoredValue"];

Yes, it is. Going over a full walkthrough of how to do this would probably exceed the length of a reasonable StackOverflow answer, so I'll refer you to this very extensive tutorial by Rajdeep Dua.

The relevant code would look like this:

// Store item in local storage:function setItem(key, value) {  try {    log("Storing [" + key + ":" + value + "]");    window.localStorage.removeItem(key);      // <-- Local storage!    window.localStorage.setItem(key, value);  // <-- Local storage!  } catch(e) {    log("Error inside setItem");    log(e);  }  log("Return from setItem" + key + ":" +  value);}// Gets item from local storage with specified key.function getItem(key) {  var value;  log('Retrieving key [' + key + ']');  try {    value = window.localStorage.getItem(key);  // <-- Local storage!  }catch(e) {    log("Error inside getItem() for key:" + key);  log(e);  value = "null";  }  log("Returning value: " + value);  return value;}// Clears all key/value pairs in local storage.function clearStrg() {  log('about to clear local storage');  window.localStorage.clear(); // <-- Local storage!  log('cleared');}function log(txt) {  if(logging) {    console.log(txt);  }}

Chrome also supports the HTML5 Web Database spec. This gives you a local SQL database, so you can do more complex things than simply storing name/value pairs in Local Storage.