Extension Storage API: expose storage quota information to extensions, via:

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

Index: chrome/test/data/extensions/api_test/settings/simple_test/background.js
diff --git a/chrome/test/data/extensions/api_test/settings/simple_test/background.js b/chrome/test/data/extensions/api_test/settings/simple_test/background.js
index 85f5e628128985966e8f47fbcd53035ee9a0eee7..72632860717dcc1355894c408b149977041f68d5 100644
--- a/chrome/test/data/extensions/api_test/settings/simple_test/background.js
+++ b/chrome/test/data/extensions/api_test/settings/simple_test/background.js
@@ -291,12 +291,55 @@ chrome.test.runTests([
     test(stage0);
   },
 
+
+  function quota() {
+    // Just check that the constants are defined; no need to be forced to
+    // update them here as well if/when they change.
+    chrome.test.assertTrue(chrome.storage.sync.QUOTA_BYTES > 0);
+    chrome.test.assertTrue(chrome.storage.sync.QUOTA_BYTES_PER_ITEM > 0);
+    chrome.test.assertTrue(chrome.storage.sync.MAX_ITEMS > 0);
+
+    chrome.test.assertTrue(chrome.storage.local.QUOTA_BYTES > 0);
+    chrome.test.assertEq('undefined',
+                         typeof chrome.storage.local.QUOTA_BYTES_PER_ITEM);
+    chrome.test.assertEq('undefined',
+                         typeof chrome.storage.local.MAX_ITEMS);
+
+    var area = chrome.storage.sync;
+    function stage0() {
+      area.getBytesInUse(null, stage1);
+    }
+    function stage1(bytesInUse) {
+      chrome.test.assertEq(0, bytesInUse);
+      area.set({ a: 42, b: 43, c: 44 }, stage2);
+    }
+    function stage2() {
+      area.getBytesInUse(null, stage3);
+    }
+    function stage3(bytesInUse) {
+      chrome.test.assertEq(9, bytesInUse);
+      area.getBytesInUse('a', stage4);
+    }
+    function stage4(bytesInUse) {
+      chrome.test.assertEq(3, bytesInUse);
+      area.getBytesInUse(['a', 'b'], stage5);
+    }
+    function stage5(bytesInUse) {
+      chrome.test.assertEq(6, bytesInUse);
+      chrome.test.succeed();
+    }
+    area.clear(stage0);
+  },
+
+  // NOTE: throttling test must come last, since each test runs with a single
+  // quota.
   function throttling() {
     // We can only really test one of the namespaces since they will all get
     // throttled together.
     var api = chrome.storage.sync;
 
-    // Should get throttled after 1000 calls.
+    // Should get throttled after 1000 calls (though in reality will be fewer
+    // due to previous tests).
     var maxRequests = 1001;
 
     function next() {
@@ -310,4 +353,5 @@ chrome.test.runTests([
     }
     api.clear(next);
   }
+
 ]);