Get the default device scale factor from monitor

ui/aura/monitor_manager.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 UI_AURA_MONITOR_MANAGER_H_
 #define UI_AURA_MONITOR_MANAGER_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 24 matching lines @@
   }
   static bool use_fullscreen_host_window() {
     return use_fullscreen_host_window_;
   }
 
   // Creates a monitor from string spec. 100+200-1440x800 creates monitor
   // whose size is 1440x800 at the location (100, 200) in screen's coordinates.
   // The location can be omitted and be just "1440x800", which creates
   // monitor at the origin of the screen. An empty string creates
   // the monitor with default size.
-  static gfx::Monitor CreateMonitorFromSpec(const std::string& spec);
+  //  The device scale factor can be specifeid by "*", like "1280x780*2",
+  // or |default_device_scale_factor| will be used if omitted.
+  static gfx::Monitor CreateMonitorFromSpec(

[sadrul, 2012/04/30 15:15:49]

It would be very nice to remove the '*' bit from the string-spec. Having
multiple ways of setting the scale-factor from the command-line is rather
confusing.

[oshima, 2012/04/30 17:25:25]

This allow us to test multi densities environment, so we should remove default
scale factor if we have to remove one of them. I can't do this now however
because the device is using this value now. We need to fix powerd to report
correct DPI first.

+      float default_device_scale_factor, const std::string& spec);
 
   // A utility function to create a root window for primary monitor.
   static RootWindow* CreateRootWindowForPrimaryMonitor();
 
   MonitorManager();
   virtual ~MonitorManager();
 
+  float default_device_scale_factor() const {
+    return default_device_scale_factor_;
+  }
+
   // Adds/removes MonitorObservers.
   void AddObserver(MonitorObserver* observer);
   void RemoveObserver(MonitorObserver* observer);
 
   // Called when monitor configuration has changed. The new monitor
   // configurations is passed as a vector of Monitor object, which
   // contains each monitor's new infomration.
   virtual void OnNativeMonitorsChanged(
       const std::vector<gfx::Monitor>& monitors) = 0;
 
@@ skipping 21 matching lines @@
   void NotifyMonitorAdded(const gfx::Monitor& monitor);
   void NotifyMonitorRemoved(const gfx::Monitor& monitor);
 
  private:
   // If set before the RootWindow is created, the host window will cover the
   // entire monitor.  Note that this can still be overridden via the
   // switches::kAuraHostWindowSize flag.
   static bool use_fullscreen_host_window_;
 
   ObserverList<MonitorObserver> observers_;
+
+  float default_device_scale_factor_;
   DISALLOW_COPY_AND_ASSIGN(MonitorManager);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MONITOR_MANAGER_H_