Revert of Support early associated interface binding on ChannelMojo

ipc/ipc.mojom

Index: ipc/ipc.mojom
diff --git a/ipc/ipc.mojom b/ipc/ipc.mojom
index 2896fc2ca224dd46e0a5dc4e0ddd827cb7a90e42..28d73fbea63bed5aca12cb544c25c8ee0eb801fd 100644
--- a/ipc/ipc.mojom
+++ b/ipc/ipc.mojom
@@ -22,13 +22,17 @@
 interface GenericInterface {};
 
 interface Channel {
-  // Informs the remote end of this client's PID. Must be called exactly once,
-  // before any calls to Receive() below.
-  SetPeerPid(int32 pid);
-
-  // Transmits a classical Chrome IPC message.
   Receive(array<uint8> data, array<SerializedHandle>? handles);
 
-  // Requests a Channel-associated interface.
   GetAssociatedInterface(string name, associated GenericInterface& request);
 };
+
+// An interface for connecting a pair of Channel interfaces representing a
+// bidirectional IPC channel.
+interface Bootstrap {
+  // Initializes a Chrome IPC channel over |to_client_channel| and
+  // |to_server_channel|. Each side also sends its PID to the other side.
+  Init(associated Channel& to_client_channel,
+       associated Channel to_server_channel,
+       int32 pid) => (int32 pid);
+};