Introduce FormFetcher::Clone

components/password_manager/core/browser/fake_form_fetcher.h

Index: components/password_manager/core/browser/fake_form_fetcher.h
diff --git a/components/password_manager/core/browser/fake_form_fetcher.h b/components/password_manager/core/browser/fake_form_fetcher.h
index 93fa7e398460a209c21899490f61acdcc5fc0b53..01aaf111acd642666f1ecebe2746dd7fcafb9dcb 100644
--- a/components/password_manager/core/browser/fake_form_fetcher.h
+++ b/components/password_manager/core/browser/fake_form_fetcher.h
@@ -61,6 +61,9 @@ class FakeFormFetcher : public FormFetcher {
   // Only sets the internal state to WAITING, no call to PasswordStore.
   void Fetch() override;
 
+  // A no-op, returns null.
+  std::unique_ptr<FormFetcher> Clone() override;
+
  private:
   std::set<Consumer*> consumers_;
   State state_ = State::NOT_WAITING;