shill: Add http_proxy class

The http_proxy adds a device/connection based proxy that guarantees
to the caller that its HTTP request will go out a particular device's
connection.  DNS requests occur through a bound socket to this device
and goes to DNS servers configured on this connection.  HTTP requests
will also be bound to this interface.  This facility will be used by
a number of peripheral bits including portal detection, activation and
cashew.

BUG=chromium-os:21664
TEST=New unit test.  New (disabled) functional test, against which I
can run "curl -x" and Chrome with manual proxy settings.

Change-Id: I0d59bf0ae27d3538ef359f786742f5c2f1d6fef9
Reviewed-on: https://gerrit.chromium.org/gerrit/10165
Reviewed-by: Thieu Le <thieule@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
Commit-Ready: Paul Stewart <pstew@chromium.org>
diff --git a/glib_io_ready_handler.cc b/glib_io_ready_handler.cc
index bb4fa7c..b72ca0e 100644
--- a/glib_io_ready_handler.cc
+++ b/glib_io_ready_handler.cc
@@ -14,13 +14,14 @@
 static gboolean DispatchIOHandler(GIOChannel *chan,
                                   GIOCondition cond,
                                   gpointer data) {
-  Callback1<int>::Type *callback = static_cast<Callback1<int>::Type *>(data);
+  Callback1<int>::Type *callback =
+    reinterpret_cast<Callback1<int>::Type *>(data);
+
+  callback->Run(g_io_channel_unix_get_fd(chan));
 
   if (cond & (G_IO_NVAL | G_IO_HUP | G_IO_ERR))
     return FALSE;
 
-  callback->Run(g_io_channel_unix_get_fd(chan));
-
   return TRUE;
 }