Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

chrome/renderer/net/net_error_helper.cc

 // Copyright (c) 2013 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 "chrome/renderer/net/net_error_helper.h"
 
 #include <memory>
 #include <string>
 #include <utility>
 
@@ skipping 145 matching lines @@
                         OnSetNavigationCorrectionInfo);
 #if defined(OS_ANDROID)
     IPC_MESSAGE_HANDLER(ChromeViewMsg_SetHasOfflinePages, OnSetHasOfflinePages)
 #endif
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
   return handled;
 }
 
+void NetErrorHelper::OnDestruct() {
+  delete this;
+}
+
 void NetErrorHelper::NetworkStateChanged(bool enabled) {
   core_->NetworkStateChanged(enabled);
 }
 
 void NetErrorHelper::GetErrorHTML(const blink::WebURLError& error,
                                   bool is_failed_post,
                                   bool is_ignoring_cache,
                                   std::string* error_html) {
   core_->GetErrorHTML(GetFrameType(render_frame()), error, is_failed_post,
                       is_ignoring_cache, error_html);
@@ skipping 191 matching lines @@
     const blink::WebURLResponse& response,
     const std::string& data) {
   tracking_fetcher_.reset();
 }
 
 #if defined(OS_ANDROID)
 void NetErrorHelper::OnSetHasOfflinePages(bool has_offline_pages) {
   core_->OnSetHasOfflinePages(has_offline_pages);
 }
 #endif  // defined(OS_ANDROID)