Quota: Remove virtual qualifier from ~QutaTemporaryStorageEvictor

The class has no superclasses or subclasses, so it is confusing for the
reader to see the virtual qualifier here. This change clarifies for the
readers how this class is used.

Change-Id: I22fc58f88a0dd7091c530ce55357ed783d4b46c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1506377
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638318}

storage/browser/quota/quota_temporary_storage_evictor.h

@@ -74,7 +74,7 @@ class COMPONENT_EXPORT(STORAGE_BROWSER) QuotaTemporaryStorageEvictor {
 
   QuotaTemporaryStorageEvictor(QuotaEvictionHandler* quota_eviction_handler,
                                int64_t interval_ms);
-  virtual ~QuotaTemporaryStorageEvictor();
+  ~QuotaTemporaryStorageEvictor();
 
   void GetStatistics(std::map<std::string, int64_t>* statistics);
   void ReportPerRoundHistogram();