Update storage::QuotaTask TODO to use OnceCallback.

Fixed: 1007832
Change-Id: If378af56a88dea07b90ee12ebadd407e967ad46d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1943490
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720482}

storage/browser/quota/quota_task.h

@@ -27,7 +27,7 @@ class QuotaTaskObserver;
 // This class is not thread-safe and it's subclasses need not be either.
 // CallCompleted(), Abort(), and DeleteSoon() must be called on the same thread
 // that is the constructor is called on.
-// TODO(kinuko): Revise this using base::Callback.
+// TODO(kinuko): Revise this using base::OnceCallback.
 class QuotaTask {
  public:
   void Start();