Include mojo/public/cpp/bindings/binding.h wherever mojo::Binding<> is used.

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

 // Copyright 2014 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 <stdio.h>
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
 #include "mojo/public/c/system/macros.h"
+#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/interface_impl.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 #include "mojo/public/cpp/bindings/lib/connector.h"
 #include "mojo/public/cpp/bindings/lib/filter_chain.h"
 #include "mojo/public/cpp/bindings/lib/message_header_validator.h"
 #include "mojo/public/cpp/bindings/lib/router.h"
 #include "mojo/public/cpp/bindings/lib/validation_errors.h"
 #include "mojo/public/cpp/bindings/message.h"
 #include "mojo/public/cpp/bindings/tests/validation_test_input_parser.h"
 #include "mojo/public/cpp/environment/environment.h"
@@ skipping 405 matching lines @@
       MakeRequest<IntegrationTestInterface>(testee_endpoint().Pass()));
   binding.internal_router()->EnableTestingMode();
 
   RunValidationTests("integration_intf_rqst", test_message_receiver());
   RunValidationTests("integration_msghdr", test_message_receiver());
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace mojo