Extension Settings API: throttle the API in the same way that the Bookmarks API

chrome/test/data/extensions/api_test/settings/simple_test/background.html

 <script>
 // Calls chrome.test.succeed after the settings have been cleared for the next
 // test.
 function succeed() {
   chrome.experimental.settings.clear(chrome.test.succeed);
 }
 
 chrome.test.runTests([
   function getWhenEmpty() {
     function stage0() {
@@ skipping 267 matching lines @@
       }, stage8);
     }
     function stage8(settings) {
       chrome.test.assertEq({
         'foo': 'defaultBar',
         'baz': {}
       }, settings);
       succeed();
     }
     stage0();
+  },
+
+  function throttling() {
+    // Should get throttled after 1000 calls.
+    var maxRequests = 1001;
+    function next() {
+      chrome.experimental.settings.clear((--maxRequests > 0) ? next : done);
+    }
+    function done() {
+      chrome.test.assertEq(
+          "This request exceeds available quota.",
+          chrome.extension.lastError.message);
+      succeed();
+    }
+    chrome.experimental.settings.clear(next);
   }
 ]);
 </script>