Rewrite of sigslot that avoids vtables.

webrtc/base/sigslot_unittest.cc

Index: webrtc/base/sigslot_unittest.cc
diff --git a/webrtc/base/sigslot_unittest.cc b/webrtc/base/sigslot_unittest.cc
index 4d3041d1326ecac9e5a61bf353bcbbf8f52c82d2..d7d64b4393545d1e32425b2c030aa102fb4f24b9 100644
--- a/webrtc/base/sigslot_unittest.cc
+++ b/webrtc/base/sigslot_unittest.cc
@@ -103,12 +103,8 @@ class multi_threaded_local_fake : public sigslot::multi_threaded_local {
   multi_threaded_local_fake() : lock_count_(0), unlock_count_(0) {
   }
 
-  virtual void lock() {
-    ++lock_count_;
-  }
-  virtual void unlock() {
-    ++unlock_count_;
-  }
+  void lock() { ++lock_count_; }
+  void unlock() { ++unlock_count_; }
 
   int lock_count() { return lock_count_; }