Adds switch to disable generating mouse events from touch events and

ui/aura/env.h

Index: ui/aura/env.h
diff --git a/ui/aura/env.h b/ui/aura/env.h
index 033456561f3dc2451bd78d50b9c5fb07dad52487..d3925c771c98a4e7433b6e05fc916f56224d18dc 100644
--- a/ui/aura/env.h
+++ b/ui/aura/env.h
@@ -45,6 +45,10 @@ class AURA_EXPORT Env {
     mouse_button_flags_ = mouse_button_flags;
   }
 
+  // Whether any touch device is currently down.
+  bool is_touch_down() const { return is_touch_down_; }
+  void set_touch_down(bool value) { is_touch_down_ = value; }
+
   client::StackingClient* stacking_client() { return stacking_client_; }
   void set_stacking_client(client::StackingClient* stacking_client) {
     stacking_client_ = stacking_client;
@@ -78,6 +82,7 @@ class AURA_EXPORT Env {
 
   static Env* instance_;
   int mouse_button_flags_;
+  bool is_touch_down_;
   client::StackingClient* stacking_client_;
   scoped_ptr<MonitorManager> monitor_manager_;