Point out in the comments the equivalence of two observer functions.

content/public/browser/render_process_host_observer.h

 // Copyright 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_OBSERVER_H_
 
 #include "base/process/kill.h"
 #include "base/process/process_handle.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 class RenderProcessHost;
 
 // An observer API implemented by classes which are interested
 // in RenderProcessHost lifecycle events.
 class CONTENT_EXPORT RenderProcessHostObserver {
  public:
   // This method is invoked when a render process exited (either normally or
   // with a crash). To determine if the process closed normally or crashed,
   // examine the |status| parameter.
+  //
+  // Note that this is equivalent to WebContentsObserver::RenderProcessGone().
   virtual void RenderProcessExited(RenderProcessHost* host,
                                    base::ProcessHandle handle,
                                    base::TerminationStatus status,
                                    int exit_code) {}
 
   // This method is invoked when the observed RenderProcessHost itself is
   // destroyed.
   virtual void RenderProcessHostDestroyed(RenderProcessHost* host) {}
 
  protected:
   virtual ~RenderProcessHostObserver() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_OBSERVER_H_