[SystemInfo API] Rewrite DisplayInfoProvider without SystemInfoProvider.

chrome/browser/extensions/api/system_display/display_info_provider_chromeos.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 "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/shell.h"
 #include "base/message_loop/message_loop_proxy.h"
@@ skipping 337 matching lines @@
                          new_bounds_origin.y() - target.bounds().y());
     UpdateDisplayLayout(primary.bounds(), primary.id(),
                         target_bounds, target.id());
   }
 
   return true;
 }
 
 }  // namespace
 
-void DisplayInfoProvider::SetInfo(const std::string& display_id,
+bool DisplayInfoProvider::SetInfo(const std::string& display_id,
                                   const DisplayProperties& info,
-                                  const SetInfoCallback& callback) {
-  std::string error;
-  bool success = SetInfoImpl(display_id, info, &error);
-  base::MessageLoopProxy::current()->PostTask(
-      FROM_HERE,
-      base::Bind(callback, success, error));
+                                  std::string* error) {
+  return SetInfoImpl(display_id, info, error);
 }
 
 void DisplayInfoProvider::UpdateDisplayUnitInfoForPlatform(
     const gfx::Display& display,
     extensions::api::system_display::DisplayUnitInfo* unit) {
 
   ash::internal::DisplayManager* display_manager
       = ash::Shell::GetInstance()->display_manager();
   unit->name = display_manager->GetDisplayNameForId(display.id());
   if (display_manager->IsMirrored()) {
     unit->mirroring_source_id =
         base::Int64ToString(display_manager->mirrored_display().id());
   }
 
   const float dpi = display.device_scale_factor() * kDpi96;
   unit->dpi_x = dpi;
   unit->dpi_y = dpi;
 
   const gfx::Insets overscan_insets =
       display_manager->GetOverscanInsets(display.id());
   unit->overscan.left = overscan_insets.left();
   unit->overscan.top = overscan_insets.top();
   unit->overscan.right = overscan_insets.right();
   unit->overscan.bottom = overscan_insets.bottom();
 }
 
 }  // namespace extensions