Remove the "one at a time" restriction from the browsingData API

chrome/browser/browsing_data/browsing_data_remover.h

Index: chrome/browser/browsing_data/browsing_data_remover.h
diff --git a/chrome/browser/browsing_data/browsing_data_remover.h b/chrome/browser/browsing_data/browsing_data_remover.h
index 0487471bb6fc970b36cae7a4b2b1ef3c3b3884b6..ac8db556ed8da52cb2ca4db9924266be00333b66 100644
--- a/chrome/browser/browsing_data/browsing_data_remover.h
+++ b/chrome/browser/browsing_data/browsing_data_remover.h
@@ -305,9 +305,6 @@ class BrowsingDataRemover : public KeyedService
       Observer* observer);
 
  private:
-  // The clear API needs to be able to toggle removing_ in order to test that
-  // only one BrowsingDataRemover instance can be called at a time.
-  FRIEND_TEST_ALL_PREFIXES(ExtensionBrowsingDataTest, OneAtATime);
   // Testing the private RemovalTask.
   FRIEND_TEST_ALL_PREFIXES(BrowsingDataRemoverTest, MultipleTasks);