Revert of Deletes mojo::Callback

mojo/public/cpp/bindings/tests/handle_passing_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdint.h>
 #include <utility>
 
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "mojo/public/cpp/bindings/binding.h"
@@ skipping 42 matching lines @@
   base::Closure closure_;
 };
 int ImportedInterfaceImpl::do_something_count_ = 0;
 
 class SampleNamedObjectImpl : public sample::NamedObject {
  public:
   explicit SampleNamedObjectImpl(InterfaceRequest<sample::NamedObject> request)
       : binding_(this, std::move(request)) {}
   void SetName(const mojo::String& name) override { name_ = name; }
 
-  void GetName(const GetNameCallback& callback) override {
+  void GetName(const mojo::Callback<void(mojo::String)>& callback) override {
     callback.Run(name_);
   }
 
  private:
   std::string name_;
   StrongBinding<sample::NamedObject> binding_;
 };
 
 class SampleFactoryImpl : public sample::Factory {
  public:
@@ skipping 60 matching lines @@
       InterfaceRequest<sample::NamedObject> object_request) override {
     EXPECT_TRUE(object_request.is_pending());
     new SampleNamedObjectImpl(std::move(object_request));
   }
 
   // These aren't called or implemented, but exist here to test that the
   // methods are generated with the correct argument types for imported
   // interfaces.
   void RequestImportedInterface(
       InterfaceRequest<imported::ImportedInterface> imported,
-      const RequestImportedInterfaceCallback& callback) override {}
+      const mojo::Callback<void(InterfaceRequest<imported::ImportedInterface>)>&
+          callback) override {}
   void TakeImportedInterface(
       imported::ImportedInterfacePtr imported,
-      const TakeImportedInterfaceCallback& callback) override {}
+      const mojo::Callback<void(imported::ImportedInterfacePtr)>& callback)
+      override {}
 
  private:
   ScopedMessagePipeHandle pipe1_;
   Binding<sample::Factory> binding_;
 };
 
 class HandlePassingTest : public testing::Test {
  public:
   HandlePassingTest() {}
 
@@ skipping 202 matching lines @@
   run_loop.Run();
   run_loop2.Run();
 
   EXPECT_EQ(std::string("object1"), name1);
   EXPECT_EQ(std::string("object2"), name2);
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace mojo