aura: Replace UI-feature GYP flags with switches.

ash/ash_switches.cc

Index: ash/ash_switches.cc
diff --git a/ash/ash_switches.cc b/ash/ash_switches.cc
index 10b71adc98c7b7d89cae9739a3cd1f2e73899007..f7ef7d1b1350d0db80e4ac0692897877737589d0 100644
--- a/ash/ash_switches.cc
+++ b/ash/ash_switches.cc
@@ -11,9 +11,20 @@
 namespace ash {
 namespace switches {
 
+// Force the "compact" window mode regardless of the value of kAuraWindowMode.
+// This can be used to override a value set in chrome://flags.
+// TODO(derat): Remove this once the normal mode is usable on all platforms.
+const char kAuraForceCompactWindowMode[] = "aura-force-compact-window-mode";
+
 // Use Google-style dialog box frames.
 const char kAuraGoogleDialogFrames[] = "aura-google-dialog-frames";
 
+// (Most) Chrome OS hardware reports ACPI power button releases correctly.
+// Standard hardware reports releases immediately after presses.  If set, we
+// lock the screen or shutdown the system immediately in response to a press
+// instead of displaying an interactive animation.
+const char kAuraLegacyPowerButton[] = "aura-legacy-power-button";
+
 // Avoid drawing drop shadows under windows.
 const char kAuraNoShadows[] = "aura-no-shadows";