Mojo C++ Bindings: Introduce mojo::SupportsStrongBinding

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 36 matching lines @@
 
   static int do_something_count() { return do_something_count_; }
 
  private:
   static int do_something_count_;
   Binding<ImportedInterface> binding_;
   base::Closure closure_;
 };
 int ImportedInterfaceImpl::do_something_count_ = 0;
 
-class SampleNamedObjectImpl : public sample::NamedObject {
+class SampleNamedObjectImpl
+    : public SupportsStrongBinding<sample::NamedObject> {
  public:
   SampleNamedObjectImpl() {}
 
   void SetName(const std::string& name) override { name_ = name; }
 
   void GetName(const GetNameCallback& callback) override {
     callback.Run(name_);
   }
 
  private:
@@ skipping 281 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