Polish the SystemInfoProvider template code and refactor StorageInfoProvider based on it

chrome/browser/extensions/api/system_info_storage/system_info_storage_api.h

Index: chrome/browser/extensions/api/system_info_storage/system_info_storage_api.h
diff --git a/chrome/browser/extensions/api/system_info_storage/system_info_storage_api.h b/chrome/browser/extensions/api/system_info_storage/system_info_storage_api.h
index f925f170a7674782aab2f49754b8feccd456c6c8..eb9ccaa0883420d3c458ae55f322e33a0a4f626d 100644
--- a/chrome/browser/extensions/api/system_info_storage/system_info_storage_api.h
+++ b/chrome/browser/extensions/api/system_info_storage/system_info_storage_api.h
@@ -5,6 +5,7 @@
 #define CHROME_BROWSER_EXTENSIONS_API_SYSTEM_INFO_STORAGE_SYSTEM_INFO_STORAGE_API_H_
 
 #include "chrome/browser/extensions/extension_function.h"
+#include "chrome/common/extensions/api/experimental_system_info_storage.h"
 
 namespace extensions {
 
@@ -13,20 +14,15 @@ namespace extensions {
 class SystemInfoStorageGetFunction : public AsyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.systemInfo.storage.get");
-
   SystemInfoStorageGetFunction();
 
  private:
   virtual ~SystemInfoStorageGetFunction();
-
-  // AsyncExtensionFunction implementation.
   virtual bool RunImpl() OVERRIDE;
 
-  // Called on FILE thread to get storage information
-  void WorkOnFileThread();
-
-  // Responds the result back to UI thread
-  void RespondOnUIThread(bool success);
+  void OnGetStorageInfoCompleted(
+      const api::experimental_system_info_storage::StorageInfo& info,
+      bool success);
 };
 
 }  // namespace extensions