Add shortcut keys to ui scaling

ash/ash_switches.cc

Index: ash/ash_switches.cc
diff --git a/ash/ash_switches.cc b/ash/ash_switches.cc
index e40324ee30e4ecf344203dc18c88850dc2ae1d54..381f723dc9b69e96c2a609002797288da93e13d4 100644
--- a/ash/ash_switches.cc
+++ b/ash/ash_switches.cc
@@ -61,6 +61,12 @@ const char kAshDisablePerAppLauncher[] = "ash-disable-per-app-launcher";
 // Disables immersive fullscreen mode.
 const char kAshDisableImmersiveMode[] = "ash-disable-immersive-mode";
 
+// Disables display rotation.
+const char kAshDisableDisplayRotation[] = "ash-disable-display-rotation";
+
+// Disables ui scaling.
+const char kAshDisableUIScaling[] = "ash-disable-ui-scaling";
+
 // Enable advanced gestures (e.g. for window management).
 const char kAshEnableAdvancedGestures[] = "ash-enable-advanced-gestures";