Makes it easier to snap or dock windows near the edges when using touch

ash/wm/workspace/snap_sizer.h

Index: ash/wm/workspace/snap_sizer.h
diff --git a/ash/wm/workspace/snap_sizer.h b/ash/wm/workspace/snap_sizer.h
index b32c3c8c3102d528ccce3acbc75786c80757656d..03eaf93f96566d11b557bbba97b48ba34febe2c3 100644
--- a/ash/wm/workspace/snap_sizer.h
+++ b/ash/wm/workspace/snap_sizer.h
@@ -31,9 +31,13 @@ class ASH_EXPORT SnapSizer {
 
   enum InputType {
     TOUCH_MAXIMIZE_BUTTON_INPUT,
+    TOUCH_DRAG_INPUT,
     OTHER_INPUT
   };
 
+  // Snapping is made easier with a touch drag when using touchscreen.
+  static const int kScreenEdgeInsetForTouchDrag;
+
   // Set |input_type| to |TOUCH_MAXIMIZE_BUTTON_INPUT| when called by a touch
   // operation by the maximize button. This will allow the user to snap resize
   // the window beginning close to the border.