High contrast mode support for multiple displays.

ash/high_contrast/high_contrast_controller.h

Index: ash/high_contrast/high_contrast_controller.h
diff --git a/ash/high_contrast/high_contrast_controller.h b/ash/high_contrast/high_contrast_controller.h
index df151832efecf4614489aea52eb133dcf341cc3c..2afd60b3aa4ee1afb1f173cb5419d2819059d874 100644
--- a/ash/high_contrast/high_contrast_controller.h
+++ b/ash/high_contrast/high_contrast_controller.h
@@ -20,11 +20,17 @@ class ASH_EXPORT HighContrastController {
 
   ~HighContrastController() {}
 
+  // Set high contrast mode and update all available displays.
   void SetEnabled(bool enabled);
 
+  // Update high contrast mode on the just added display.
+  void OnRootWindowAdded(aura::RootWindow* root_window);
+
  private:
-  aura::RootWindow* root_window_;
+  // Update high contrast mode on the passed display.
+  void UpdateDisplay(aura::RootWindow* root_window);
 
+  // Indicates if the high contrast mode is enabled or disabled.
   bool enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(HighContrastController);