Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

content/renderer/dom_serializer_browsertest.cc

 // Copyright (c) 2010 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 <stddef.h>
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
@@ skipping 57 matching lines @@
   LoadObserver(RenderView* render_view, const base::Closure& quit_closure)
       : RenderViewObserver(render_view),
         quit_closure_(quit_closure) {}
 
   void DidFinishLoad(blink::WebLocalFrame* frame) override {
     if (frame == render_view()->GetWebView()->mainFrame())
       quit_closure_.Run();
   }
 
  private:
+  // RenderViewObserver implementation.
+  void OnDestruct() override { delete this; }
+
   base::Closure quit_closure_;
 };
 
 class DomSerializerTests : public ContentBrowserTest,
                            public WebFrameSerializerClient {
  public:
   DomSerializerTests() : serialization_reported_end_of_data_(false) {}
 
   void SetUpCommandLine(base::CommandLine* command_line) override {
     command_line->AppendSwitch(switches::kSingleProcess);
@@ skipping 768 matching lines @@
   NavigateToURL(shell(), file_url);
 
   PostTaskToInProcessRendererAndWait(
         base::Bind(
             &DomSerializerTests::
                 SubResourceForElementsInNonHTMLNamespaceOnRenderer,
             base::Unretained(this), file_url));
 }
 
 }  // namespace content