Sync SurfaceView position changes to parent render.

In order to provide pixel perfect movement of SurfaceViews
'within' other views (e.g. scrolling) we need to be able to
synchronize the attached (parent window) painting with the
movement of the SurfaceView (recall, SurfaceViews are positioned
behind their attached windows and the parent must render a
transparent region for the SurfaceView to appear). Provide
a new WindowManager method to reposition an attaching window
(that is to say, a window which has an attached window like
SurfaceView) and defer the transaction until the parent frame.
SurfaceView is hooked up to use this for movement. This is still
'racy' in the hardware accelerated case as the render thread
could be on either side of dequeing the frame we are working on.

Bug: 22802885
Change-Id: I025d2bdcbe15c1c11047cc0dbca2cf2b7d67c632
diff --git a/services/core/java/com/android/server/wm/Session.java b/services/core/java/com/android/server/wm/Session.java
index 1f62bc1..c47c377 100644
--- a/services/core/java/com/android/server/wm/Session.java
+++ b/services/core/java/com/android/server/wm/Session.java
@@ -187,6 +187,12 @@
         mService.removeWindow(this, window);
     }
 
+    @Override
+    public void repositionChild(IWindow window, int x, int y, long deferTransactionUntilFrame,
+             Rect outFrame) {
+        mService.repositionChild(this, window, x, y, deferTransactionUntilFrame, outFrame);
+    }
+
     public int relayout(IWindow window, int seq, WindowManager.LayoutParams attrs,
             int requestedWidth, int requestedHeight, int viewFlags,
             int flags, Rect outFrame, Rect outOverscanInsets, Rect outContentInsets,