[SystemInfo API] Rewrite DisplayInfoProvider without SystemInfoProvider.

chrome/browser/extensions/api/system_display/display_info_provider_gtk.cc

 // Copyright 2013 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 "chrome/browser/extensions/api/system_display/display_info_provider.h"
 
 #include <gdk/gdk.h>
 
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
 
 namespace extensions {
 
-void DisplayInfoProvider::SetInfo(
-    const std::string& display_id,
+bool DisplayInfoProvider::SetInfo(const std::string& display_id,
     const api::system_display::DisplayProperties& info,
-    const SetInfoCallback& callback) {
-  base::MessageLoopProxy::current()->PostTask(
-      FROM_HERE,
-      base::Bind(callback, false, "Not implemented"));
+    std::string* error) {
+  *error = "Not Implemented";
+  return false;
 }
 
 void DisplayInfoProvider::UpdateDisplayUnitInfoForPlatform(
     const gfx::Display& display,
     extensions::api::system_display::DisplayUnitInfo* unit) {
   // TODO(Haojian): determine the DPI of the display
   GdkScreen* screen = gdk_screen_get_default();
   // The |id| in Display for GTK is the monitor index.
   gint monitor_num = static_cast<gint>(display.id());
   char* monitor_name = reinterpret_cast<char*>(gdk_screen_get_monitor_plug_name(
        screen, monitor_num));
   unit->name = std::string(monitor_name);
 }
 
 }  // namespace extensions