Update from chromium https://crrev.com/302282

net/tools/flip_server/mem_cache_test.cc

Index: net/tools/flip_server/mem_cache_test.cc
diff --git a/net/tools/flip_server/mem_cache_test.cc b/net/tools/flip_server/mem_cache_test.cc
index bb01907a96c405d9f3768ea8d2b6f87c39f7264a..87dca685bf23efbcf22b54d08ee32a692bb797ca 100644
--- a/net/tools/flip_server/mem_cache_test.cc
+++ b/net/tools/flip_server/mem_cache_test.cc
@@ -13,10 +13,9 @@ namespace {
 
 class MemoryCacheWithFakeReadToString : public MemoryCache {
  public:
-  virtual ~MemoryCacheWithFakeReadToString() {}
+  ~MemoryCacheWithFakeReadToString() override {}
 
-  virtual void ReadToString(const char* filename,
-                            std::string* output) override {
+  void ReadToString(const char* filename, std::string* output) override {
     *output = data_map_[filename];
   }