Update pre-drag lifecycle for apps with shortcuts.

- First of all, deferred drag has been renamed to pre-drag
  to avoid confusion with the existing deferred end drag.
- For normal drags, the cycle is still startDrag -->
  onDragStart --> onDrop --> onDropComplete --> onDragEnd.
- Pre-drags have two additional callbacks: onPreDragStart
  and onPreDragEnd. onPreDragStart is called between
  startDrag and onDragStart, and onPreDragEnd is called
  at the same time as onDragStart or onDragEnd.
- If the pre-drag has not transitioned to a full drag before
  onDragEnd, onDragStart and onDropComplete are skipped
  (onDrop is still called to allow the DragView to animate).

Change-Id: Icd7a8f75d5fcc159f9a52758c22ab6eae3edb9e2
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 47edadd..12e902a 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -164,7 +164,7 @@
     <dimen name="bg_pill_height">48dp</dimen>
     <dimen name="bg_pill_radius">24dp</dimen>
     <dimen name="deep_shortcuts_spacing">4dp</dimen>
-    <dimen name="deferred_drag_view_scale">6dp</dimen>
+    <dimen name="pre_drag_view_scale">6dp</dimen>
     <!-- an icon with shortcuts must be dragged this far before the container is removed. -->
     <dimen name="deep_shortcuts_start_drag_threshold">16dp</dimen>
     <dimen name="deep_shortcut_icon_size">36dp</dimen>