Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

components/password_manager/content/renderer/credential_manager_client.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/password_manager/content/renderer/credential_manager_client.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <utility>
@@ skipping 198 matching lines @@
 
 void CredentialManagerClient::ConnectToMojoCMIfNeeded() {
   if (mojo_cm_service_)
     return;
 
   content::RenderFrame* main_frame = render_view()->GetMainRenderFrame();
   main_frame->GetServiceRegistry()->ConnectToRemoteService(
       mojo::GetProxy(&mojo_cm_service_));
 }
 
+void CredentialManagerClient::OnDestruct() {
+  delete this;
+}
+
 }  // namespace password_manager