Revert of Style cleanup in preparation for auto-linting base/.

base/simple_thread_unittest.cc

Index: base/simple_thread_unittest.cc
diff --git a/base/simple_thread_unittest.cc b/base/simple_thread_unittest.cc
index 8bb267dc7a097bfd35fb05b5f498bfcca04450ba..639eeaeb6acfb9aea1f3cc90a70bd6d492c06794 100644
--- a/base/simple_thread_unittest.cc
+++ b/base/simple_thread_unittest.cc
@@ -27,7 +27,7 @@
 
 class WaitEventRunner : public base::DelegateSimpleThread::Delegate {
  public:
-  explicit WaitEventRunner(base::WaitableEvent* event) : event_(event) { }
+  WaitEventRunner(base::WaitableEvent* event) : event_(event) { }
   ~WaitEventRunner() { }
 
   virtual void Run() {
@@ -41,7 +41,7 @@
 
 class SeqRunner : public base::DelegateSimpleThread::Delegate {
  public:
-  explicit SeqRunner(base::AtomicSequenceNumber* seq) : seq_(seq) { }
+  SeqRunner(base::AtomicSequenceNumber* seq) : seq_(seq) { }
   virtual void Run() {
     seq_->GetNext();
   }