Revert of Deletes mojo::Callback

extensions/browser/mojo/stash_backend.cc

Index: extensions/browser/mojo/stash_backend.cc
diff --git a/extensions/browser/mojo/stash_backend.cc b/extensions/browser/mojo/stash_backend.cc
index 7da65745cd306cf5fb5184e38d0ad34cd006b1c4..8104c4d09a581caf858a0974c5c2881d1eb6cd00 100644
--- a/extensions/browser/mojo/stash_backend.cc
+++ b/extensions/browser/mojo/stash_backend.cc
@@ -27,7 +27,9 @@
 
   // StashService overrides.
   void AddToStash(mojo::Array<StashedObjectPtr> stash) override;
-  void RetrieveStash(const RetrieveStashCallback& callback) override;
+  void RetrieveStash(
+      const mojo::Callback<void(mojo::Array<StashedObjectPtr> stash)>& callback)
+      override;
 
  private:
   mojo::StrongBinding<StashService> binding_;
@@ -50,7 +52,8 @@
   backend_->AddToStash(std::move(stashed_objects));
 }
 
-void StashServiceImpl::RetrieveStash(const RetrieveStashCallback& callback) {
+void StashServiceImpl::RetrieveStash(
+    const mojo::Callback<void(mojo::Array<StashedObjectPtr>)>& callback) {
   if (!backend_) {
     callback.Run(mojo::Array<StashedObjectPtr>());
     return;