Upstream helper method to clear data using BrowserStateDataRemover.

ios/chrome/browser/signin/browser_state_data_remover.h

Index: ios/chrome/browser/signin/browser_state_data_remover.h
diff --git a/ios/chrome/browser/signin/browser_state_data_remover.h b/ios/chrome/browser/signin/browser_state_data_remover.h
index 910e12abbd42f68f632bf31dfa55e92e8bd5c8c0..fc5f2a31787d002fad1c9b065c81d8665ad6f952 100644
--- a/ios/chrome/browser/signin/browser_state_data_remover.h
+++ b/ios/chrome/browser/signin/browser_state_data_remover.h
@@ -20,6 +20,12 @@ class BrowserStateDataRemover {
   explicit BrowserStateDataRemover(ios::ChromeBrowserState* browser_state);
   ~BrowserStateDataRemover();
 
+  // Removes all bookmarks, clears all browsing data, last signed-in username
+  // and then runs |completion|. The user must be signed out when this method
+  // is called.
+  static void ClearData(ios::ChromeBrowserState* browser_state,
+                        ProceduralBlock completion);
+
   // If set then the last username will be removed from the browser state prefs
   // after the data has been wiped.
   void SetForgetLastUsername();