Revert of Remove smiluate-touch-screen-with-mouse content flag.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 44630613f35e1adaa7d80a509f0579642d69498f..c4ad822f513d5fa6c6be636550d259c06fa7980a 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -790,6 +790,11 @@
 // and study painting behavior.
 const char kShowPaintRects[]                = "show-paint-rects";
 
+// Map mouse input events into touch gesture events.  Useful for debugging touch
+// gestures without needing a touchscreen.
+const char kSimulateTouchScreenWithMouse[]  =
+    "simulate-touch-screen-with-mouse";
+
 // Runs the renderer and plugins in the same process as the browser
 const char kSingleProcess[]                 = "single-process";