Shift cookie system callbacks to OnceCallback to impedance match mojo.

chrome/browser/browsing_data/mock_browsing_data_cookie_helper.h

Index: chrome/browser/browsing_data/mock_browsing_data_cookie_helper.h
diff --git a/chrome/browser/browsing_data/mock_browsing_data_cookie_helper.h b/chrome/browser/browsing_data/mock_browsing_data_cookie_helper.h
index 7b9daf9eafde072a810878f92403976872d5781c..f6487a617c7f48df8913352c013c9d21423c52d2 100644
--- a/chrome/browser/browsing_data/mock_browsing_data_cookie_helper.h
+++ b/chrome/browser/browsing_data/mock_browsing_data_cookie_helper.h
@@ -20,8 +20,7 @@ class MockBrowsingDataCookieHelper : public BrowsingDataCookieHelper {
       net::URLRequestContextGetter* request_context_getter);
 
   // BrowsingDataCookieHelper methods.
-  void StartFetching(
-      const net::CookieStore::GetCookieListCallback& callback) override;
+  void StartFetching(const FetchCallback& callback) override;
   void DeleteCookie(const net::CanonicalCookie& cookie) override;
 
   // Adds some cookie samples.
@@ -40,7 +39,7 @@ class MockBrowsingDataCookieHelper : public BrowsingDataCookieHelper {
  private:
   ~MockBrowsingDataCookieHelper() override;
 
-  net::CookieStore::GetCookieListCallback callback_;
+  FetchCallback callback_;
 
   net::CookieList cookie_list_;