content: Cleanup class/struct forward declarations

content/browser/renderer_host/render_process_host_impl.h

 // Copyright (c) 2012 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_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 43 matching lines @@
 class AudioRendererHost;
 class ChildConnection;
 class InProcessChildThreadParams;
 class MessagePortMessageFilter;
 class NotificationMessageFilter;
 #if BUILDFLAG(ENABLE_WEBRTC)
 class P2PSocketDispatcherHost;
 #endif
 class PermissionServiceContext;
 class PeerConnectionTrackerHost;
-class RendererMainThread;
 class RenderFrameMessageFilter;
 class RenderWidgetHelper;
 class RenderWidgetHost;
 class ResourceMessageFilter;
 class StoragePartition;
 class StoragePartitionImpl;
 
 namespace mojom {
 class StoragePartitionService;
 }  // namespace mojom
@@ skipping 513 matching lines @@
       instance_weak_factory_;
 
   base::WeakPtrFactory<RenderProcessHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderProcessHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_IMPL_H_