EDK: Make mojo::embedder::AsyncWait (etc.) take an std::function instead of a base::Callback.

mojo/edk/embedder/embedder.cc

Index: mojo/edk/embedder/embedder.cc
diff --git a/mojo/edk/embedder/embedder.cc b/mojo/edk/embedder/embedder.cc
index 8f814076723658bfe642691a72599a9906b00d08..09690f433bbf02f32d29cf34a196f2f9d34aac41 100644
--- a/mojo/edk/embedder/embedder.cc
+++ b/mojo/edk/embedder/embedder.cc
@@ -95,7 +95,7 @@ void Init(std::unique_ptr<PlatformSupport> platform_support) {
 
 MojoResult AsyncWait(MojoHandle handle,
                      MojoHandleSignals signals,
-                     const base::Callback<void(MojoResult)>& callback) {
+                     const std::function<void(MojoResult)>& callback) {
   return internal::g_core->AsyncWait(handle, signals, callback);
 }