Style cleanup in preparation for auto-linting base/.

base/lazy_instance_unittest.cc

Index: base/lazy_instance_unittest.cc
diff --git a/base/lazy_instance_unittest.cc b/base/lazy_instance_unittest.cc
index cf17a84e67a36af789c4fe453b63c63ff3de46b1..d55f66489389a30f99c67ef90e15397633c8db62 100644
--- a/base/lazy_instance_unittest.cc
+++ b/base/lazy_instance_unittest.cc
@@ -41,7 +41,9 @@ int SlowConstructor::constructed = 0;
 
 class SlowDelegate : public base::DelegateSimpleThread::Delegate {
  public:
-  SlowDelegate(base::LazyInstance<SlowConstructor>* lazy) : lazy_(lazy) { }
+  explicit SlowDelegate(base::LazyInstance<SlowConstructor>* lazy)
+      : lazy_(lazy) {}
+
   virtual void Run() {
     EXPECT_EQ(12, lazy_->Get().some_int());
     EXPECT_EQ(12, lazy_->Pointer()->some_int());