Decouple IPC::MessageFilter from IPC::Channel

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 66cbbcf07f6d979a629e60363068d586d449450d..5a339203070bd5fd04a88ffb70d9ae2ba46ac60b 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -43,6 +43,7 @@
 #include "content/browser/browser_child_process_host_impl.h"
 #include "content/browser/browser_main.h"
 #include "content/browser/browser_main_loop.h"
+#include "content/browser/browser_message_filter_peer.h"
 #include "content/browser/browser_plugin/browser_plugin_message_filter.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/device_sensors/device_motion_message_filter.h"
@@ -450,6 +451,7 @@ RenderProcessHostImpl::RenderProcessHostImpl(
       mojo_activation_required_(false),
       visible_widgets_(0),
       backgrounded_(true),
+      filter_peer_(new BrowserMessageFilterPeer()),
       is_initialized_(false),
       id_(ChildProcessHostImpl::GenerateChildProcessUniqueId()),
       browser_context_(browser_context),
@@ -1411,6 +1413,7 @@ void RenderProcessHostImpl::OnChannelConnected(int32 peer_pid) {
       IPC::Logging::GetInstance()->Enabled()));
 #endif
 
+  filter_peer_->set_pid(peer_pid);
   tracked_objects::ThreadData::Status status =
       tracked_objects::ThreadData::status();
   Send(new ChildProcessMsg_SetProfilerStatus(status));
@@ -1600,6 +1603,8 @@ IPC::ChannelProxy* RenderProcessHostImpl::GetChannel() {
 }
 
 void RenderProcessHostImpl::AddFilter(BrowserMessageFilter* filter) {
+  // OnFilterRemovedFromHost() is called by BrowserMessageFilter::Internal.
+  filter->OnFilterAddedToHost(filter_peer_.get());
   channel_->AddFilter(filter->GetFilter());
 }