Make IPC::Channel polymorphic

ipc/ipc_channel_proxy.cc

Index: ipc/ipc_channel_proxy.cc
diff --git a/ipc/ipc_channel_proxy.cc b/ipc/ipc_channel_proxy.cc
index ceffb9474c47290cc11c4590cf1f680d8bc70fa6..2f2a893edb10e6187629398c186fd08af43df456 100644
--- a/ipc/ipc_channel_proxy.cc
+++ b/ipc/ipc_channel_proxy.cc
@@ -52,7 +52,7 @@ void ChannelProxy::Context::CreateChannel(const IPC::ChannelHandle& handle,
                                           const Channel::Mode& mode) {
   DCHECK(!channel_);
   channel_id_ = handle.name;
-  channel_ = Channel::CreateByModeForProxy(handle, mode, this);
+  channel_ = Channel::Create(handle, mode, this);
 }
 
 bool ChannelProxy::Context::TryFilters(const Message& message) {
@@ -95,7 +95,7 @@ bool ChannelProxy::Context::OnMessageReceivedNoFilter(const Message& message) {
 // Called on the IPC::Channel thread
 void ChannelProxy::Context::OnChannelConnected(int32 peer_pid) {
   // We cache off the peer_pid so it can be safely accessed from both threads.
-  peer_pid_ = channel_->peer_pid();
+  peer_pid_ = channel_->GetPeerPID();
 
   // Add any pending filters.  This avoids a race condition where someone
   // creates a ChannelProxy, calls AddFilter, and then right after starts the