Be a little more precise in the wording of comments for process death.

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.
+  // This method is invoked when the process of the observed RenderProcessHost
+  // exits (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().
+  // This will cause a call to WebContentsObserver::RenderProcessGone() for
+  // active renderer processes; for code that needs to be a WebContentsObserver

[nasko, 2015/07/10 07:48:54]

This isn't quite correct I think. Last time I poked at it,
WCO::RenderProcessGone is called only for the top-level frame, even with
--site-per-process. It isn't quite clear what the behavior in that mode should
be and whether we need overlap between these two observer interfaces.

[Avi (use Gerrit), 2015/07/10 15:29:20]

I see that. WebContentsImpl::RenderViewTerminated does a check at the top to
eliminate the pending RVH, but that will also eliminate all non-top-level RVHs.
I will adjust the comment.

+  // anyway, consider whether that API might be a better choice.
   virtual void RenderProcessExited(RenderProcessHost* host,
                                    base::TerminationStatus status,
                                    int exit_code) {}
 
   // This method is invoked when the observed RenderProcessHost itself is
   // destroyed. This is guaranteed to be the last call made to the observer.
   virtual void RenderProcessHostDestroyed(RenderProcessHost* host) {}
 
  protected:
   virtual ~RenderProcessHostObserver() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_OBSERVER_H_