Make quota logic obey durable storage permission

extensions/shell/browser/shell_special_storage_policy.cc

Index: extensions/shell/browser/shell_special_storage_policy.cc
diff --git a/extensions/shell/browser/shell_special_storage_policy.cc b/extensions/shell/browser/shell_special_storage_policy.cc
index 5ed1b50f4253725f8601048e12593438d3039d01..d43c71bfdd786986958a68e26f4346c77cc604fa 100644
--- a/extensions/shell/browser/shell_special_storage_policy.cc
+++ b/extensions/shell/browser/shell_special_storage_policy.cc
@@ -20,6 +20,12 @@ bool ShellSpecialStoragePolicy::IsStorageUnlimited(const GURL& origin) {
   return true;
 }
 
+bool ShellSpecialStoragePolicy::IsStorageDurable(const GURL& origin) {
+  // The plan is to forbid extensions from acquiring the durable storage
+  // permission because they can specify 'unlimitedStorage' in the manifest.
+  return false;
+}
+
 bool ShellSpecialStoragePolicy::IsStorageSessionOnly(const GURL& origin) {
   return false;
 }