Quota: Minor cleanup for QuotaManager.

Replace the deprecated DISALLOW_COPY_AND_ASSIGN macro with deleted
copy constructor and assignment operator.

Change-Id: I63c8719a9ee49b602d3a6e5e9c74925f2699551a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2590690
Commit-Queue: Darwin Huang <huangdarwin@chromium.org>
Reviewed-by: Darwin Huang <huangdarwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836896}

storage/browser/quota/quota_manager.h

@@ -147,6 +147,8 @@ class COMPONENT_EXPORT(STORAGE_BROWSER) QuotaManager
                base::RepeatingClosure quota_change_callback,
                scoped_refptr<SpecialStoragePolicy> special_storage_policy,
                const GetQuotaSettingsFunc& get_settings_function);
+  QuotaManager(const QuotaManager&) = delete;
+  QuotaManager& operator=(const QuotaManager&) = delete;
 
   const QuotaSettings& settings() const { return settings_; }
   void SetQuotaSettings(const QuotaSettings& settings);
@@ -581,8 +583,6 @@ class COMPONENT_EXPORT(STORAGE_BROWSER) QuotaManager
   SEQUENCE_CHECKER(sequence_checker_);
 
   base::WeakPtrFactory<QuotaManager> weak_factory_{this};
-
-  DISALLOW_COPY_AND_ASSIGN(QuotaManager);
 };
 
 }  // namespace storage