Support running with mojo:debugger in devtools.

mojo/devtools/common/devtoolslib/shell.py

Index: mojo/devtools/common/devtoolslib/shell.py
diff --git a/mojo/devtools/common/devtoolslib/shell.py b/mojo/devtools/common/devtoolslib/shell.py
index a757c3ceceb93e0589bacf8bacf1273e1a2f04fa..30211fcda0e6f5101d4f7953fffd89a80b9b5aa2 100644
--- a/mojo/devtools/common/devtoolslib/shell.py
+++ b/mojo/devtools/common/devtoolslib/shell.py
@@ -22,6 +22,14 @@ class Shell(object):
     """
     raise NotImplementedError()
 
+  def ForwardHostPortToShell(self, host_port):
+    """Forwards a port on the host machine to the same port wherever the shell
+    is running.
+
+    This is a no-op if the shell is running locally.
+    """
+    raise NotImplementedError()
+
   def Run(self, arguments):
     """Runs the shell with given arguments until shell exits, passing the stdout
     mingled with stderr produced by the shell onto the stdout.