Remove handler from MessagePumpForIO::IOContext.

ipc/ipc_channel_win.cc

Index: ipc/ipc_channel_win.cc
diff --git a/ipc/ipc_channel_win.cc b/ipc/ipc_channel_win.cc
index 404e688a212367303b3d9ccee8eba0a4b1da0957..8bdb7ae33b370cd644431547a4df0de22cb3fc88 100644
--- a/ipc/ipc_channel_win.cc
+++ b/ipc/ipc_channel_win.cc
@@ -28,10 +28,7 @@
 
 namespace IPC {
 
-ChannelWin::State::State(ChannelWin* channel) : is_pending(false) {
-  memset(&context.overlapped, 0, sizeof(context.overlapped));
-  context.handler = channel;
-}
+ChannelWin::State::State() = default;
 
 ChannelWin::State::~State() {
   static_assert(offsetof(ChannelWin::State, context) == 0,
@@ -43,8 +40,6 @@ ChannelWin::ChannelWin(const IPC::ChannelHandle& channel_handle,
                        Mode mode,
                        Listener* listener)
     : ChannelReader(listener),
-      input_state_(this),
-      output_state_(this),
       peer_pid_(base::kNullProcessId),
       waiting_connect_(mode & MODE_SERVER_FLAG),
       processing_incoming_(false),