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

chrome/browser/automation/testing_automation_provider.cc

 // 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.
 
 #include "chrome/browser/automation/testing_automation_provider.h"
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 97 matching lines @@
 #include "chrome/common/chrome_view_type.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/url_pattern.h"
 #include "chrome/common/extensions/url_pattern_set.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/common/url_constants.h"
 #include "content/browser/plugin_service.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/tab_contents/interstitial_page.h"
+#include "content/common/child_process_host.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/common/common_param_traits.h"
 #include "net/base/cookie_store.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
 #include "ui/base/events.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/base/ui_base_types.h"
 #include "webkit/glue/webdropdata.h"
 #include "webkit/plugins/webplugininfo.h"
@@ skipping 6303 matching lines @@
 
   Send(reply_message_);
   redirect_query_ = 0;
   reply_message_ = NULL;
 }
 
 void TestingAutomationProvider::OnRemoveProvider() {
   if (g_browser_process)
     g_browser_process->GetAutomationProviderList()->RemoveProvider(this);
 }