components: Cleanup class/struct fwd declarations

components/spellcheck/browser/spellcheck_platform.h

 // Copyright (c) 2011 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.
 
 // This file defines the interface that any platform-specific spellchecker
 // needs to implement in order to be used by the browser.
 
 #ifndef COMPONENTS_SPELLCHECK_BROWSER_SPELLCHECK_PLATFORM_H_
 #define COMPONENTS_SPELLCHECK_BROWSER_SPELLCHECK_PLATFORM_H_
 
 #include <string>
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/strings/string16.h"
 
 struct SpellCheckResult;
 
-namespace content {
-class BrowserMessageFilter;
-}  // namespace content
-
 namespace spellcheck_platform {
 
 typedef base::Callback<void(
         const std::vector<SpellCheckResult>& /* results */)>
             TextCheckCompleteCallback;
 
 // Get the languages supported by the platform spellchecker and store them in
 // |spellcheck_languages|. Note that they must be converted to
 // Chromium style codes (en-US not en_US). See spellchecker.cc for a full list.
 void GetAvailableLanguages(std::vector<std::string>* spellcheck_languages);
@@ skipping 73 matching lines @@
  public:
   ScopedEnglishLanguageForTest();
   ~ScopedEnglishLanguageForTest();
  private:
   SpellcheckerStateInternal* state_;
 };
 
 }  // namespace spellcheck_platform
 
 #endif  // COMPONENTS_SPELLCHECK_BROWSER_SPELLCHECK_PLATFORM_H_