[Extensions] Convert some ChromeSyncExtensionFunctions

chrome/browser/chromeos/extensions/file_manager/private_api_strings.h

Index: chrome/browser/chromeos/extensions/file_manager/private_api_strings.h
diff --git a/chrome/browser/chromeos/extensions/file_manager/private_api_strings.h b/chrome/browser/chromeos/extensions/file_manager/private_api_strings.h
index 1ee6d64fbbeac2222e7fde802b42276e41d9adb0..2cb4970417a7b783ac2a94cd11201615965eeec9 100644
--- a/chrome/browser/chromeos/extensions/file_manager/private_api_strings.h
+++ b/chrome/browser/chromeos/extensions/file_manager/private_api_strings.h
@@ -13,8 +13,7 @@ namespace extensions {
 
 // Implements the chrome.fileManagerPrivate.getStrings method.
 // Used to get strings for the file manager from JavaScript.
-class FileManagerPrivateGetStringsFunction
-    : public ChromeSyncExtensionFunction {
+class FileManagerPrivateGetStringsFunction : public UIThreadExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("fileManagerPrivate.getStrings",
                              FILEMANAGERPRIVATE_GETSTRINGS)
@@ -24,8 +23,8 @@ class FileManagerPrivateGetStringsFunction
  protected:
   ~FileManagerPrivateGetStringsFunction() override;
 
-  // SyncExtensionFunction overrides.
-  bool RunSync() override;
+  // ExtensionFunction:
+  ResponseAction Run() override;
 };
 
 }  // namespace extensions