Linux Aura accessibility is enabled only on GNOME desktops

ui/accessibility/platform/atk_util_auralinux.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <atk/atk.h>
+#include <dbus/dbus.h>
 #include <gconf/gconf-client.h>
 #include <glib-2.0/gmodule.h>
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "ui/accessibility/platform/atk_util_auralinux.h"
 #include "ui/accessibility/platform/ax_platform_node_auralinux.h"
 
 namespace {
 
 const char kGnomeAccessibilityEnabledKey[] =
     "/desktop/gnome/interface/accessibility";
 
+const char destination[] = "org.a11y.Bus";

[Peter Lundblad, 2015/03/23 16:45:38]

Should use the naming style for constants.

+const char objectPathTheMessageShouldBeSentTo[] =

[Peter Lundblad, 2015/03/23 16:45:38]

nit: slightly verbose name.

+    "/org/a11y/bus";

[Peter Lundblad, 2015/03/23 16:45:38]

Does this fit on the previous line?

+const char interfaceToInvokeMethodOn[] =
+    "org.freedesktop.DBus.Properties";
+const char methodToInvoke[] = "Get";
+const char* interfaceName = "org.a11y.Status";
+const char* propertyName = "IsEnabled";
+
+bool AtSpiAccessibilityIsEnabled()
+{
+  DBusError error;
+  dbus_error_init(&error);
+
+  DBusConnection* connection = dbus_bus_get(DBUS_BUS_SYSTEM, &error);

[Peter Lundblad, 2015/03/23 16:45:38]

Are we leaking this connection?

+  if (!connection) {
+    dbus_error_free(&error);
+    return false;
+  }
+
+  DBusMessage* message = dbus_message_new_method_call(destination,
+                                            objectPathTheMessageShouldBeSentTo,
+                                            interfaceToInvokeMethodOn,
+                                            methodToInvoke);
+  if (!message) {
+    dbus_error_free(&error);
+    return false;
+  }
+
+  dbus_message_append_args(message,
+                           DBUS_TYPE_STRING,
+                           &interfaceName,
+                           DBUS_TYPE_STRING,
+                           &propertyName,
+                           DBUS_TYPE_INVALID);
+
+  DBusMessage* reply = dbus_connection_send_with_reply_and_block(connection,
+                                                                 message,
+                                                                 -1,
+                                                                 &error);
+
+  if (dbus_error_is_set(&error)) {
+    dbus_message_unref(message);
+    dbus_error_free(&error);
+    return false;
+  }
+
+  DBusMessageIter iterator, subIterator;
+  bool shouldBeEnabled = false;
+
+  dbus_message_iter_init(reply, &iterator);
+  dbus_message_iter_recurse(&iterator, &subIterator);
+  switch (dbus_message_iter_get_arg_type(&subIterator)) {
+    case DBUS_TYPE_BOOLEAN:
+      dbus_message_iter_get_basic(&subIterator, &shouldBeEnabled);
+    break;
+      break;

[Peter Lundblad, 2015/03/23 16:45:38]

Not reached.

+  }
+
+  if (message)

[Peter Lundblad, 2015/03/23 16:45:38]

When can message be null?

+    dbus_message_unref(message);
+
+  if (reply)

[Peter Lundblad, 2015/03/23 16:45:38]

When can reply be null?

+    dbus_message_unref(reply);
+
+  dbus_error_free(&error);
+
+  return shouldBeEnabled;
+}
+
 bool ShouldEnableAccessibility() {
+  if (AtSpiAccessibilityIsEnabled())
+    return true;
+
   GConfClient* client = gconf_client_get_default();

[Peter Lundblad, 2015/03/23 16:45:38]

 Is the rest of this function redundant or is there a case
where your new code would return false but accessibility in gnome would
still be enabled?  If it is not redundant, maybe add some explanation
in a comment, but if it is, we should clean it up.

   if (!client) {
     LOG(ERROR) << "gconf_client_get_default failed";
     return false;
   }
 
   GError* error = nullptr;
   gboolean value = gconf_client_get_bool(client,
                                          kGnomeAccessibilityEnabledKey,
                                          &error);
   if (error) {
@@ skipping 120 matching lines @@
   if (g_module_symbol(bridge, "gnome_accessibility_module_init",
                       (gpointer *)&gnome_accessibility_module_init)) {
     (*gnome_accessibility_module_init)();
   }
 }
 
 AtkUtilAuraLinux::~AtkUtilAuraLinux() {
 }
 
 }  // namespace ui