Minimize black screen during the boot with multi displays

ash/display/display_change_observer_x11.cc

 // Copyright (c) 2012 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 "ash/display/display_change_observer_x11.h"
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 76 matching lines @@
   base::MessagePumpAuraX11::Current()->AddDispatcherForRootWindow(this);
 }
 
 DisplayChangeObserverX11::~DisplayChangeObserverX11() {
   base::MessagePumpAuraX11::Current()->RemoveDispatcherForRootWindow(this);
 }
 
 bool DisplayChangeObserverX11::Dispatch(const base::NativeEvent& event) {
   if (event->type - xrandr_event_base_ == RRScreenChangeNotify) {
     NotifyDisplayChange();
+    XRRUpdateConfiguration(event);

[oshima, 2013/01/25 21:22:52]

according to http://www.x.org/archive/current/doc/man/man3/Xrandr.3.xhtml,

we're supposed to call this.

   }
   return true;
 }
 
 void DisplayChangeObserverX11::NotifyDisplayChange() {
   XRRScreenResources* screen_resources =
       XRRGetScreenResources(xdisplay_, x_root_window_);
   std::map<XID, XRRCrtcInfo*> crtc_info_map;
 
   for (int c = 0; c < screen_resources->ncrtc; c++) {
@@ skipping 79 matching lines @@
       iter->set_id(id);
       ++id;
     }
   }
   // DisplayManager can be null during the boot.
   Shell::GetInstance()->display_manager()->OnNativeDisplaysChanged(displays);
 }
 
 }  // namespace internal
 }  // namespace ash