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 7e1bff9427561110c763cec46747b853d83f645b..28067cf74679dd48db8f713ff1584f580bc6524d 100644
--- a/ipc/mojo/ipc_channel_mojo_host.cc
+++ b/ipc/mojo/ipc_channel_mojo_host.cc
@@ -30,7 +30,6 @@ class ChannelMojoHost::ChannelDelegate
   // 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();
@@ -73,11 +72,6 @@ void ChannelMojoHost::ChannelDelegate::OnChannelCreated(
   channel_ = channel;
 }
 
-scoped_refptr<base::TaskRunner>
-ChannelMojoHost::ChannelDelegate::GetIOTaskRunner() {
-  return io_task_runner_;
-}
-
 void ChannelMojoHost::ChannelDelegate::OnClientLaunched(
     base::ProcessHandle process) {
   if (channel_)