Merge changes from topic "shadow-in-app"

* changes:
  Remove DragDropController#prepareDrag()
  Create a drag shadow surface in app process,

diff --cc core/java/android/view/IWindowSession.aidl
Simple merge

diff --cc core/java/android/view/View.java
Simple merge

diff --cc services/core/java/com/android/server/wm/DisplayContent.java
Simple merge

diff --cc services/core/java/com/android/server/wm/Session.java
Simple merge