Add ability to set resolution on external display

ash/display/display_change_observer_x11.h

 // 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.
 
 #ifndef ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_X11_H
 #define ASH_DISPLAY_DISPLAY_CHANGE_OBSERVER_X11_H
 
 #include <X11/Xlib.h>
 
 // Xlib.h defines RootWindow.
@@ skipping 13 matching lines @@
     : public chromeos::OutputConfigurator::StateController,
       public chromeos::OutputConfigurator::Observer,
       public ShellObserver {
  public:
   DisplayChangeObserverX11();
   virtual ~DisplayChangeObserverX11();
 
   // chromeos::OutputConfigurator::StateController overrides:
   virtual chromeos::OutputState GetStateForDisplayIds(
       const std::vector<int64>& outputs) const OVERRIDE;
+  virtual bool GetResolutionForDisplayId(
+      int64 display_id,
+      size_t* width,

[Daniel Erat, 2013/07/31 17:34:05]

why size_t? are you worried that these won't fit in ints? note that e.g.
gfx::Size uses ints.

[oshima, 2013/07/31 21:59:49]

sorry I forgot to fix this. I first thought this is what xrandr uses, which I
was wrong. Fixed.

+      size_t* height) const OVERRIDE;
 
   // Overriden from chromeos::OutputConfigurator::Observer:
   virtual void OnDisplayModeChanged() OVERRIDE;
 
   // Overriden from ShellObserver:
   virtual void OnAppTerminating() OVERRIDE;
 
  private:
   Display* xdisplay_;
 
   ::Window x_root_window_;
 
   int xrandr_event_base_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayChangeObserverX11);
 };
 
-// Returns true if the size info in the output_info isn't valid
-// and should be ignored. This is exposed for testing.
-// |mm_width| and |mm_height| are given in millimeters.
-ASH_EXPORT bool ShouldIgnoreSize(unsigned long mm_width,
-                                 unsigned long mm_height);
-
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_AURA_DISPLAY_CHANGE_OBSERVER_X11_H