Created skeleton for switch access component extension.

chrome/browser/chromeos/accessibility/accessibility_manager.h

Index: chrome/browser/chromeos/accessibility/accessibility_manager.h
diff --git a/chrome/browser/chromeos/accessibility/accessibility_manager.h b/chrome/browser/chromeos/accessibility/accessibility_manager.h
index 4acbe97d26f53f2591e893079908d06250888644..da1ecde8516f91e61588d7e35910d231fd6b1162 100644
--- a/chrome/browser/chromeos/accessibility/accessibility_manager.h
+++ b/chrome/browser/chromeos/accessibility/accessibility_manager.h
@@ -418,6 +418,8 @@ class AccessibilityManager
   std::unique_ptr<chromeos::SelectToSpeakEventHandler>
       select_to_speak_event_handler_;
 
+  std::unique_ptr<AccessibilityExtensionLoader> switch_access_loader_;
+
   base::WeakPtrFactory<AccessibilityManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AccessibilityManager);