Hide docked windows behind a flag

ash/common/ash_switches.h

Index: ash/common/ash_switches.h
diff --git a/ash/common/ash_switches.h b/ash/common/ash_switches.h
index 08548f65c07e8f7b671d7db7575ea26c2c7a76f9..28f4430f9b26d4f32fd8b370e546e1cf095004f1 100644
--- a/ash/common/ash_switches.h
+++ b/ash/common/ash_switches.h
@@ -27,6 +27,7 @@ ASH_EXPORT extern const char kAshEnableFullscreenAppList[];
 ASH_EXPORT extern const char kAshEnableMagnifierKeyScroller[];
 ASH_EXPORT extern const char kAshEnablePalette[];
 ASH_EXPORT extern const char kAshEnablePaletteOnAllDisplays[];
+ASH_EXPORT extern const char kAshEnableDockedWindows[];
 ASH_EXPORT extern const char kAshEnableTouchView[];
 ASH_EXPORT extern const char kAshEnableMirroredScreen[];
 ASH_EXPORT extern const char kAshDisableStableOverviewOrder[];
@@ -42,6 +43,9 @@ ASH_EXPORT extern const char kAuraLegacyPowerButton[];
 // True if the pointer (cursor) position should be kept inside root windows.
 ASH_EXPORT bool ConstrainPointerToRoot();
 
+// True if docking windows right or left is enabled.
+ASH_EXPORT bool DockedWindowsEnabled();
+
 }  // namespace switches
 }  // namespace ash