Snap screen rotation animation layers to final position if the animation is aborted.

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.

TBR=oshima@chromium.org

TEST=ScreenRotationAnimationTest.LayerTransformGetsSetToTargetWhenAborted

BUG=496986
Review URL: https://codereview.chromium.org/1315573003

Cr-Commit-Position: refs/heads/master@{#348734}
(cherry picked from commit ca01f9e55651e4a7285f551e83bd561b01787c19)

Committed: https://chromium.googlesource.com/chromium/src/+/a46fd8c576eafecfef5abeffbd0be73f4c3de7b2

[bruthig, 2015-09-23 18:33:33]

oshima@, I've TBR'ed you on this merge back to M45.  Can you take a look when
you get a chance?

[bruthig, 2015-09-23 18:36:45]

Committed patchset #1 (id:1) manually as
a46fd8c576eafecfef5abeffbd0be73f4c3de7b2 (presubmit successful).