Snap screen rotation animation layers to final position if the animation is aborted.
Some users were seeing incorrectly aligned and rotated backgrounds while
at the lock screen. It was possible that the session state animations
were aborting the screen rotation animations prematurely and thus they
would get stuck in a bad position.
TEST=ScreenRotationAnimationTest.LayerTransformGetsSetToTargetWhenAborted
BUG=496986
Review URL: https://codereview.chromium.org/
1315573003
Cr-Commit-Position: refs/heads/master@{#348734}