Add a convenience typedef LazyInstance<T>::Leaky to avoid repeating T.

base/lazy_instance.h

Index: base/lazy_instance.h
diff --git a/base/lazy_instance.h b/base/lazy_instance.h
index ededc73cbbaeba9d426c85e7d85ef4a9be7b0ed6..3d8507845fec921427183197e4d0fb6364948259 100644
--- a/base/lazy_instance.h
+++ b/base/lazy_instance.h
@@ -73,6 +73,11 @@ struct DefaultLazyInstanceTraits {
   }
 };
 
+// Use LazyInstance<T>::Leaky for a less-verbose call-site typedef; e.g.:
+// base::LazyInstance<T>::Leaky my_leaky_lazy_instance;
+// instead of:
+// base::LazyInstance<T, LeakyLazyInstanceTraits<T> > my_leaky_lazy_instance;
+// (especially when T is MyLongTypeNameImplClientHolderFactory).
 template <typename Type>
 struct LeakyLazyInstanceTraits {
   static const bool kRegisterOnExit = false;
@@ -117,6 +122,10 @@ class LazyInstance {
   // the OnExit member function, where needed.
   // ~LazyInstance() {}
 
+  // Convenience typedef to avoid having to repeat Type for leaky lazy
+  // instances.
+  typedef LazyInstance<Type, LeakyLazyInstanceTraits<Type> > Leaky;
+
   Type& Get() {
     return *Pointer();
   }