Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

components/translate/content/renderer/translate_helper.cc

 // Copyright (c) 2012 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/translate/content/renderer/translate_helper.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 620 matching lines @@
   // and may eventually become available, triggering the RESUMED event; after
   // this, everything should start being ON_TIME. This should never run more
   // than twice in a page load, under any conditions.
   // Also note that language detection is triggered off of a delay AFTER the
   // page load completed event has fired, making this very much off the critical
   // path.
   content::RenderThread::Get()->UpdateHistograms(
       content::kHistogramSynchronizerReservedSequenceNumber);
 }
 
+void TranslateHelper::OnDestruct() {
+  delete this;
+}
+
 }  // namespace translate