Remove IPC channel IDs.

ipc/ipc_channel_proxy.h

Index: ipc/ipc_channel_proxy.h
diff --git a/ipc/ipc_channel_proxy.h b/ipc/ipc_channel_proxy.h
index 9f6932dc40a8c821b8566f6495f180daed4440a5..5765630a2582349a9b470785eef7c4ae6842bd0f 100644
--- a/ipc/ipc_channel_proxy.h
+++ b/ipc/ipc_channel_proxy.h
@@ -250,8 +250,6 @@ class IPC_EXPORT ChannelProxy : public Sender, public base::NonThreadSafe {
     base::SingleThreadTaskRunner* ipc_task_runner() const {
       return ipc_task_runner_.get();
     }
-    const std::string& channel_id() const { return channel_id_; }
-
     // Dispatches a message on the listener thread.
     void OnDispatchMessage(const Message& message);
 
@@ -339,7 +337,6 @@ class IPC_EXPORT ChannelProxy : public Sender, public base::NonThreadSafe {
     // thread.
     // One exception is the thread-safe send. See the class comment.
     std::unique_ptr<Channel> channel_;
-    std::string channel_id_;
     bool channel_connected_called_;
 
     // Lock for |channel_| value. This is only relevant in the context of