content: Cleanup class/struct forward declarations

content/renderer/mojo_context_state.h

 // 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.
 
 #ifndef CONTENT_RENDERER_MOJO_CONTEXT_STATE_H_
 #define CONTENT_RENDERER_MOJO_CONTEXT_STATE_H_
 
 #include <memory>
 #include <set>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "gin/modules/module_registry_observer.h"
 #include "v8/include/v8.h"
 
 namespace blink {
 class WebFrame;
 class WebURLResponse;
 }
 
 namespace gin {
-class ContextHolder;
 struct PendingModule;
 }
 
 namespace content {
 
 class ResourceFetcher;
 class MojoMainRunner;
 enum class MojoBindingsType;
 
 // MojoContextState manages the modules needed for mojo bindings. It does this
@@ skipping 48 matching lines @@
 
   // The prefix to use for all module requests.
   const std::string module_prefix_;
 
   DISALLOW_COPY_AND_ASSIGN(MojoContextState);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MOJO_CONTEXT_STATE_H_