Standardize usage of virtual/override/final in base/

base/bind_unittest.cc

Index: base/bind_unittest.cc
diff --git a/base/bind_unittest.cc b/base/bind_unittest.cc
index ce1af1bf83f303b6e2d94f1bc900dfef41b02742..a30b7756704658a599a84e3df88e80166e731ce7 100644
--- a/base/bind_unittest.cc
+++ b/base/bind_unittest.cc
@@ -66,7 +66,7 @@ class Parent {
 
 class Child : public Parent {
  public:
-  virtual void VirtualSet() override { value = kChildValue; }
+  void VirtualSet() override { value = kChildValue; }
   void NonVirtualSet() { value = kChildValue; }
 };
 
@@ -78,7 +78,7 @@ class NoRefParent {
 };
 
 class NoRefChild : public NoRefParent {
-  virtual void VirtualSet() override { value = kChildValue; }
+  void VirtualSet() override { value = kChildValue; }
   void NonVirtualSet() { value = kChildValue; }
 };