Add ServeLocalDirectory to the shell abstraction.

mojo/devtools/common/devtoolslib/linux_shell.py

Index: mojo/devtools/common/devtoolslib/linux_shell.py
diff --git a/mojo/devtools/common/devtoolslib/linux_shell.py b/mojo/devtools/common/devtoolslib/linux_shell.py
index 30ab4e98b4c0fa8be358fdd3d1e2f423cbdf2252..4b3d98a4cd2ef636807a1620f8db2db4fb869dd4 100644
--- a/mojo/devtools/common/devtoolslib/linux_shell.py
+++ b/mojo/devtools/common/devtoolslib/linux_shell.py
@@ -5,6 +5,7 @@
 import subprocess
 
 from devtoolslib.shell import Shell
+from devtoolslib import http_server
 
 
 class LinuxShell(Shell):
@@ -20,6 +21,22 @@ class LinuxShell(Shell):
     self.executable_path = executable_path
     self.command_prefix = command_prefix if command_prefix else []
 
+  def ServeLocalDirectory(self, local_dir_path, port=0):
+    """Serves the content of the local (host) directory, making it available to
+    the shell under the url returned by the function.
+
+    The server will run on a separate thread until the program terminates. The
+    call returns immediately.
+
+    Args:
+      local_dir_path: path to the directory to be served
+      port: port at which the server will be available to the shell
+
+    Returns:
+      The url that the shell can use to access the content of |local_dir_path|.
+    """
+    return 'http://%s:%d/' % http_server.StartHttpServer(local_dir_path, port)
+
   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.