Get the default device scale factor from monitor

ui/aura/monitor_manager.h

Index: ui/aura/monitor_manager.h
diff --git a/ui/aura/monitor_manager.h b/ui/aura/monitor_manager.h
index b3886cf3e5700bc29018fe6b3b5fabc057ffee3e..e92287c4897db0780b92c50a6429bce64ef9e2e0 100644
--- a/ui/aura/monitor_manager.h
+++ b/ui/aura/monitor_manager.h
@@ -42,7 +42,10 @@ class AURA_EXPORT MonitorManager {
   // 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();
@@ -50,6 +53,10 @@ class AURA_EXPORT MonitorManager {
   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);
@@ -91,6 +98,8 @@ class AURA_EXPORT MonitorManager {
   static bool use_fullscreen_host_window_;
 
   ObserverList<MonitorObserver> observers_;
+
+  float default_device_scale_factor_;
   DISALLOW_COPY_AND_ASSIGN(MonitorManager);
 };