"typedef Foo Bar" -> "using Bar = Foo" in //mojo/edk/....

mojo/edk/system/async_waiter.h

Index: mojo/edk/system/async_waiter.h
diff --git a/mojo/edk/system/async_waiter.h b/mojo/edk/system/async_waiter.h
index df3b48203023c562431f03246dc5f8aa2d0e40e8..be228e5baa4aed9991270f63e47b471877284284 100644
--- a/mojo/edk/system/async_waiter.h
+++ b/mojo/edk/system/async_waiter.h
@@ -17,7 +17,7 @@ namespace system {
 // An |Awakable| implementation that just calls a given callback object.
 class MOJO_SYSTEM_IMPL_EXPORT AsyncWaiter final : public Awakable {
  public:
-  typedef base::Callback<void(MojoResult)> AwakeCallback;
+  using AwakeCallback = base::Callback<void(MojoResult)>;
 
   // |callback| must satisfy the same contract as |Awakable::Awake()|.
   explicit AsyncWaiter(const AwakeCallback& callback);