Don't make classes derive from ChildProcessHost, and instead have them use it through composition...

content/browser/browser_child_process_host.h

 // Copyright (c) 2011 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_BROWSER_BROWSER_CHILD_PROCESS_HOST_H_
 #define CONTENT_BROWSER_BROWSER_CHILD_PROCESS_HOST_H_
 #pragma once
 
 #include <list>
 
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/process.h"
 #include "base/synchronization/waitable_event_watcher.h"
 #include "content/browser/child_process_launcher.h"
-#include "content/common/child_process_host.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/child_process_data.h"
+#include "content/public/common/child_process_host_delegate.h"
+#include "ipc/ipc_message.h"
+
+class ChildProcessHost;
 
 namespace base {
 class WaitableEvent;
 }
 
 // Plugins/workers and other child processes that live on the IO thread should
 // derive from this class.
 //
 // [Browser]RenderProcessHost is the main exception that doesn't derive from
 // this class. That project lives on the UI thread.
 class CONTENT_EXPORT BrowserChildProcessHost :
-    public ChildProcessHost,
+    public content::ChildProcessHostDelegate,
     public ChildProcessLauncher::Client,
-    public base::WaitableEventWatcher::Delegate {
+    public base::WaitableEventWatcher::Delegate,
+    public IPC::Message::Sender {
  public:
   virtual ~BrowserChildProcessHost();
 
   virtual void OnWaitableEventSignaled(
       base::WaitableEvent* waitable_event) OVERRIDE;
 
   // Terminates all child processes and deletes each ChildProcessHost instance.
   static void TerminateAll();
 
   // The Iterator class allows iteration through either all child processes, or
   // ones of a specific type, depending on which constructor is used.  Note that
   // this should be done from the IO thread and that the iterator should not be
   // kept around as it may be invalidated on subsequent event processing in the
   // event loop.
   class CONTENT_EXPORT Iterator {
    public:
     Iterator();
     explicit Iterator(content::ProcessType type);
     BrowserChildProcessHost* operator->() { return *iterator_; }
     BrowserChildProcessHost* operator*() { return *iterator_; }
     BrowserChildProcessHost* operator++();
     bool Done();
 
    private:
     bool all_;
     content::ProcessType type_;
     std::list<BrowserChildProcessHost*>::iterator iterator_;
   };
 
+  // IPC::Message::Sender override
+  virtual bool Send(IPC::Message* message) OVERRIDE;
+
   const content::ChildProcessData& data() const { return data_; }
   content::ProcessType type() const { return data_.type; }
   const string16& name() const { return data_.name; }
   base::ProcessHandle handle() const { return data_.handle; }
   int id() const { return data_.id; }
 
  protected:
   explicit BrowserChildProcessHost(content::ProcessType type);
 
   // Derived classes call this to launch the child process asynchronously.
@@ skipping 24 matching lines @@
   // was killed (for posix, as returned from waitpid(), for Windows,
   // as returned from GetExitCodeProcess()).
   virtual void OnProcessWasKilled(int exit_code) {}
 
   // Returns the termination status of a child.  |exit_code| is the
   // status returned when the process exited (for posix, as returned
   // from waitpid(), for Windows, as returned from
   // GetExitCodeProcess()).  |exit_code| may be NULL.
   virtual base::TerminationStatus GetChildTerminationStatus(int* exit_code);
 
-  // Overrides from ChildProcessHost
-  virtual void OnChannelConnected(int32 peer_pid) OVERRIDE;
+  // ChildProcessHostDelegate implementation:
+  virtual bool CanShutdown() OVERRIDE;
   virtual void OnChildDisconnected() OVERRIDE;
   virtual void ShutdownStarted() OVERRIDE;
-  // Extends the base class implementation and removes this host from
-  // the host list. Calls ChildProcessHost::ForceShutdown
-  virtual void ForceShutdown() OVERRIDE;
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
+  virtual void OnChannelConnected(int32 peer_pid) OVERRIDE;
+
+  // Removes this host from the host list. Calls ChildProcessHost::ForceShutdown
+  void ForceShutdown();
 
   // Controls whether the child process should be terminated on browser
   // shutdown. Default is to always terminate.
   void SetTerminateChildOnShutdown(bool terminate_on_shutdown);
 
   // Sends the given notification on the UI thread.
   void Notify(int type);
 
+  ChildProcessHost* child_process_host() const {
+    return child_process_host_.get();
+  }
   void set_name(const string16& name) { data_.name = name; }
   void set_handle(base::ProcessHandle handle) { data_.handle = handle; }
 
  private:
   // By using an internal class as the ChildProcessLauncher::Client, we can
   // intercept OnProcessLaunched and do our own processing before
   // calling the subclass' implementation.
   class ClientHook : public ChildProcessLauncher::Client {
    public:
     explicit ClientHook(BrowserChildProcessHost* host);
     virtual void OnProcessLaunched() OVERRIDE;
    private:
     BrowserChildProcessHost* host_;
   };
 
   content::ChildProcessData data_;
+  scoped_ptr<ChildProcessHost> child_process_host_;
 
   ClientHook client_;
   scoped_ptr<ChildProcessLauncher> child_process_;
 #if defined(OS_WIN)
   base::WaitableEventWatcher child_watcher_;
 #else
   base::WeakPtrFactory<BrowserChildProcessHost> task_factory_;
 #endif
   bool disconnect_was_alive_;
 };
 
 #endif  // CONTENT_BROWSER_BROWSER_CHILD_PROCESS_HOST_H_