tree e42e75bd915ec915421189f04adcbb92957edd27
parent 6b6fc5634c7d32a16a9005c14e134fcaf37ed4c8
author George Mount <mount@google.com> 1467922385 -0700
committer George Mount <mount@google.com> 1475768368 -0700

Optimize Fragment operations so that minimal work is done.

Bug 29631389

When multiple operations are executed at once, they sometimes
cancel each other. For example, if the following transactions
are queued:

Transaction 1: add A
Transaction 2: replace with B

This can be trimmed down to add B.

This CL optimizes fragments in both add and pop directions.

Developers can choose not to allow optimization by
using FragmentTransaction#setAllowOptimization

Test: If6637e9f1c2a414bebaff6404efc45dd828378ad

Change-Id: Iab75be3e0aa388fc79b794e647ac6893165bebd7