Revert of ChannelMojo: Ensure that it always has ScopedIPCSupport

ipc/mojo/ipc_channel_mojo_host.cc

Index: ipc/mojo/ipc_channel_mojo_host.cc
diff --git a/ipc/mojo/ipc_channel_mojo_host.cc b/ipc/mojo/ipc_channel_mojo_host.cc
index 28067cf74679dd48db8f713ff1584f580bc6524d..7e1bff9427561110c763cec46747b853d83f645b 100644
--- a/ipc/mojo/ipc_channel_mojo_host.cc
+++ b/ipc/mojo/ipc_channel_mojo_host.cc
@@ -30,6 +30,7 @@
   // ChannelMojo::Delegate
   base::WeakPtr<Delegate> ToWeakPtr() override;
   void OnChannelCreated(base::WeakPtr<ChannelMojo> channel) override;
+  scoped_refptr<base::TaskRunner> GetIOTaskRunner() override;
 
   // Returns an weak ptr of ChannelDelegate instead of Delegate
   base::WeakPtr<ChannelDelegate> GetWeakPtr();
@@ -70,6 +71,11 @@
     base::WeakPtr<ChannelMojo> channel) {
   DCHECK(!channel_);
   channel_ = channel;
+}
+
+scoped_refptr<base::TaskRunner>
+ChannelMojoHost::ChannelDelegate::GetIOTaskRunner() {
+  return io_task_runner_;
 }
 
 void ChannelMojoHost::ChannelDelegate::OnClientLaunched(