Introduce PasswordFormManager::GrabFetcher

components/password_manager/core/browser/password_form_manager.h

Index: components/password_manager/core/browser/password_form_manager.h
diff --git a/components/password_manager/core/browser/password_form_manager.h b/components/password_manager/core/browser/password_form_manager.h
index b4cf68b064baba0f4e8d657c9e55ec74288dc1f6..8fe73d75a0dca729a16d9d8eb7a3fb07bbc36fed 100644
--- a/components/password_manager/core/browser/password_form_manager.h
+++ b/components/password_manager/core/browser/password_form_manager.h
@@ -248,9 +248,9 @@ class PasswordFormManager : public FormFetcher::Consumer {
   // a consumer of |form_fetcher_|.
   void ResetStoredMatches();
 
-  // Takes ownership of |fetcher|.
-  // TODO(crbug.com/621355) Until https://codereview.chromium.org/2758773002/,
-  // |fetcher.get()| must be the same as |form_fetcher_|.
+  // Takes ownership of |fetcher|. If |fetcher| is different from the current
+  // |form_fetcher_| then also resets matches stored from the old fetcher and
+  // adds itself as a consumer of the new one.
   void GrabFetcher(std::unique_ptr<FormFetcher> fetcher);
 
  protected: