Simplify content::AssociatedInterfaceProviderImpl

content/common/associated_interface_provider_impl.h

Index: content/common/associated_interface_provider_impl.h
diff --git a/content/common/associated_interface_provider_impl.h b/content/common/associated_interface_provider_impl.h
index 32670b2cbffce197fb0cea46a59f3aa18e773e0c..bdfd02cea1f6f8e2082a802f0c96582d2c486662 100644
--- a/content/common/associated_interface_provider_impl.h
+++ b/content/common/associated_interface_provider_impl.h
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#ifndef CONTENT_COMMON_ASSOCIATED_INTERFACE_PROVIDER_IMPL_H_
+#define CONTENT_COMMON_ASSOCIATED_INTERFACE_PROVIDER_IMPL_H_
+
 #include "content/public/common/associated_interface_provider.h"
 
 #include <stdint.h>
@@ -43,3 +46,5 @@ class AssociatedInterfaceProviderImpl : public AssociatedInterfaceProvider {
 };
 
 }  // namespace content
+
+#endif  // CONTENT_COMMON_ASSOCIATED_INTERFACE_PROVIDER_IMPL_H_