Implemented swipe to close in overview mode.

ash/ash_switches.cc

Index: ash/ash_switches.cc
diff --git a/ash/ash_switches.cc b/ash/ash_switches.cc
index f11743dd64cd94505fba3a6ea8bae96dc40aa324..05fabb240712b141c47c11189dbaf59ae48e1280 100644
--- a/ash/ash_switches.cc
+++ b/ash/ash_switches.cc
@@ -39,6 +39,10 @@ const char kAshDisableScreenOrientationLock[] =
     "ash-disable-screen-orientation-lock";
 #endif
 
+// Disables gesture swipe to close windows while in Overview mode.
+const char kAshDisableSwipeToCloseInOverviewMode[] =
+    "ash-disable-swipe-to-close-in-overview-mode";
+
 // Disable the Touch Exploration Mode. Touch Exploration Mode will no longer be
 // turned on automatically when spoken feedback is enabled when this flag is
 // set.