Make CompositorObserver’s destructor protected-and-virtual.

content/browser/renderer_host/browser_compositor_view_mac.mm

 // 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 "content/browser/renderer_host/browser_compositor_view_mac.h"
 
 #include <stdint.h>
 
 #include <utility>
 
@@ skipping 38 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RecyclableCompositorMac
 
 // A ui::Compositor and a gfx::AcceleratedWidget (and helper) that it draws
 // into. This structure is used to efficiently recycle these structures across
 // tabs (because creating a new ui::Compositor for each tab would be expensive
 // in terms of time and resources).
 class RecyclableCompositorMac : public ui::CompositorObserver {
  public:
-  virtual ~RecyclableCompositorMac();
+  ~RecyclableCompositorMac() override;
 
   // Create a compositor, or recycle a preexisting one.
   static std::unique_ptr<RecyclableCompositorMac> Create();
 
   // Delete a compositor, or allow it to be recycled.
   static void Recycle(std::unique_ptr<RecyclableCompositorMac> compositor);
 
   // Indicate that the recyclable compositor should be destroyed, and no future
   // compositors should be recycled.
   static void DisableRecyclingForShutdown();
@@ skipping 376 matching lines @@
 void BrowserCompositorMac::OnBeginFrame(const cc::BeginFrameArgs& args) {
   client_->BrowserCompositorMacSendBeginFrame(args);
 }
 
 bool BrowserCompositorMac::IsAutoResizeEnabled() const {
   NOTREACHED();
   return false;
 }
 
 }  // namespace content