Check the IME component extension's availability on linux_chromeos, so that system fallback VK can …

chrome/browser/chromeos/input_method/component_extension_ime_manager_impl.h

 // Copyright 2013 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 CHROME_BROWSER_CHROMEOS_INPUT_METHOD_COMPONENT_EXTENSION_IME_MANAGER_IMPL_H_
 #define CHROME_BROWSER_CHROMEOS_INPUT_METHOD_COMPONENT_EXTENSION_IME_MANAGER_IMPL_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 45 matching lines @@
   // kInputComponents key from manifest. This function returns true on success,
   // otherwise retrun false. This function must be called on FILE thread.
   static bool ReadEngineComponent(
       const ComponentExtensionIME& component_extension,
       const base::DictionaryValue& dict,
       ComponentExtensionEngine* out);
 
   // The list of component extension IME.
   std::vector<ComponentExtensionIME> component_extension_list_;
 
-  // For checking the function should be called on UI thread.
-  base::ThreadChecker thread_checker_;
-  base::WeakPtrFactory<ComponentExtensionIMEManagerImpl> weak_ptr_factory_;
-
   DISALLOW_COPY_AND_ASSIGN(ComponentExtensionIMEManagerImpl);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_INPUT_METHOD_COMPONENT_EXTENSION_IME_MANAGER_IMPL_H_