Avoid using declarations in headers which introduce symbol conflicts.

third_party/WebKit/Source/modules/storage/InspectorDOMStorageAgent.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 47 matching lines @@
                                   StorageType,
                                   SecurityOrigin*);
 
  private:
   explicit InspectorDOMStorageAgent(Page*);
 
   // InspectorBaseAgent overrides.
   void restore() override;
 
   // protocol::Dispatcher::DOMStorageCommandHandler overrides.
-  Response enable() override;
-  Response disable() override;
-  Response clear(std::unique_ptr<protocol::DOMStorage::StorageId>) override;
+  protocol::Response enable() override;
+  protocol::Response disable() override;
+  protocol::Response clear(
+      std::unique_ptr<protocol::DOMStorage::StorageId>) override;
 
-  Response getDOMStorageItems(
+  protocol::Response getDOMStorageItems(
       std::unique_ptr<protocol::DOMStorage::StorageId>,
       std::unique_ptr<protocol::Array<protocol::Array<String>>>* entries)
       override;
-  Response setDOMStorageItem(std::unique_ptr<protocol::DOMStorage::StorageId>,
-                             const String& key,
-                             const String& value) override;
-  Response removeDOMStorageItem(
+  protocol::Response setDOMStorageItem(
+      std::unique_ptr<protocol::DOMStorage::StorageId>,
+      const String& key,
+      const String& value) override;
+  protocol::Response removeDOMStorageItem(
       std::unique_ptr<protocol::DOMStorage::StorageId>,
       const String& key) override;
 
-  Response findStorageArea(std::unique_ptr<protocol::DOMStorage::StorageId>,
-                           LocalFrame*&,
-                           StorageArea*&);
+  protocol::Response findStorageArea(
+      std::unique_ptr<protocol::DOMStorage::StorageId>,
+      LocalFrame*&,
+      StorageArea*&);
   std::unique_ptr<protocol::DOMStorage::StorageId> storageId(
       SecurityOrigin*,
       bool isLocalStorage);
 
   Member<Page> m_page;
   bool m_isEnabled;
 };
 
 }  // namespace blink
 
 #endif  // !defined(InspectorDOMStorageAgent_h)