tree be35f6724ed74a7ebb4f0deb424d903eb1f96159
parent 0d48072f6047140119ff194c1194ce402fca2c0b
author Robert Carr <racarr@google.com> 1487014352 -0800
committer Robert Carr <racarr@google.com> 1488219715 -0800

Add detachChildren transaction.

Add SurfaceControl#detachChildren for use by the WindowManager.
This method is used in cases where the WM would previously preserve
windows the client tried to destroy. For example, when becoming invisible
(in the activity lifecycle sense, not in the SurfaceFlinger sense)
an app will destroy its child surfaces. Previously the WM would keep child
windows alive until the animation finishes to prevent glitches. The new
scheme for this is the WM will detach the children at this point,
at which point the parent layer becomes the owner of the children and the WM
can control the lifecycle as it wishes. I also included a test for reparentChildren
as I realized I had forgotten that.

Test: New test in Transaction_test.cpp
Change-Id: I79c22b2ccccceb9bdcc37b70c491bdf33dcf83d2