Standardize usage of virtual/override/final in chrome/browser/sync/

chrome/browser/sync/test/integration/sync_exponential_backoff_test.cc

Index: chrome/browser/sync/test/integration/sync_exponential_backoff_test.cc
diff --git a/chrome/browser/sync/test/integration/sync_exponential_backoff_test.cc b/chrome/browser/sync/test/integration/sync_exponential_backoff_test.cc
index 52737fa23c36be985e0dd435213143d6876eedc1..58ee9c3aa0f114db6093b4b1125fe837c1c6a3f9 100644
--- a/chrome/browser/sync/test/integration/sync_exponential_backoff_test.cc
+++ b/chrome/browser/sync/test/integration/sync_exponential_backoff_test.cc
@@ -37,17 +37,17 @@ class ExponentialBackoffChecker : public SingleClientStatusChangeChecker {
     retry_verifier_.Initialize(snap);
   }
 
-  virtual ~ExponentialBackoffChecker() {}
+  ~ExponentialBackoffChecker() override {}
 
   // Checks if backoff is complete. Called repeatedly each time PSS notifies
   // observers of a state change.
-  virtual bool IsExitConditionSatisfied() override {
+  bool IsExitConditionSatisfied() override {
     const SyncSessionSnapshot& snap = service()->GetLastSessionSnapshot();
     retry_verifier_.VerifyRetryInterval(snap);
     return (retry_verifier_.done() && retry_verifier_.Succeeded());
   }
 
-  virtual std::string GetDebugMessage() const override {
+  std::string GetDebugMessage() const override {
     return base::StringPrintf("Verifying backoff intervals (%d/%d)",
                               retry_verifier_.retry_count(),
                               RetryVerifier::kMaxRetry);