extensions: Cleanup class/struct fwd declarations

extensions/renderer/extensions_renderer_client.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 EXTENSIONS_RENDERER_EXTENSIONS_RENDERER_CLIENT_H_
 #define EXTENSIONS_RENDERER_EXTENSIONS_RENDERER_CLIENT_H_
 
-class ResourceBundleSourceMap;
-
 namespace extensions {
 
 // Interface to allow the extensions module to make render-process-specific
 // queries of the embedder. Should be Set() once in the render process.
 //
 // NOTE: Methods that do not require knowledge of renderer concepts should be
 // added in ExtensionsClient (extensions/common/extensions_client.h) even if
 // they are only used in the renderer process.
 class ExtensionsRendererClient {
  public:
@@ skipping 10 matching lines @@
   // Returns the single instance of |this|.
   static ExtensionsRendererClient* Get();
 
   // Initialize the single instance.
   static void Set(ExtensionsRendererClient* client);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_EXTENSIONS_RENDERER_CLIENT_H_