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

chrome/browser/extensions/settings/failing_settings_storage.cc

Index: chrome/browser/extensions/settings/failing_settings_storage.cc
diff --git a/chrome/browser/extensions/settings/failing_settings_storage.cc b/chrome/browser/extensions/settings/failing_settings_storage.cc
index 8e15ace05b7c63d08829421008333c03a82e1f3a..b7d8dc03ebdda5992d47a9c2a7cf363e11e83d42 100644
--- a/chrome/browser/extensions/settings/failing_settings_storage.cc
+++ b/chrome/browser/extensions/settings/failing_settings_storage.cc
@@ -1,9 +1,11 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/settings/failing_settings_storage.h"
 
+#include "base/logging.h"
+
 namespace extensions {
 
 namespace {
@@ -20,6 +22,12 @@ SettingsStorage::WriteResult WriteResultError() {
 
 }  // namespace
 
+size_t FailingSettingsStorage::GetBytesInUse() {
+  // Let SettingsStorageQuotaEnforcer implement this.
+  NOTREACHED() << "Not implemented";
+  return 0;
+}
+
 SettingsStorage::ReadResult FailingSettingsStorage::Get(
     const std::string& key) {
   return ReadResultError();