Changes sequence of docked animations when evicting windows from dock. Windows that are restored into docked area are slid from below rather than from above as before. Additionally minimizing animation for the windows that no longer fit in the dock is slowed down in hopes of making it less confusing.
To allow this a new ScopedLayerAnimationSettings::LockTransitionDuration method is introduced which locks the current animation transition duration until the ScopedLayerAnimationSettings object that invoked it goes out of scope.

BUG=323188
TEST=ash_unittests --gtest_filter=WindowAnimationsTest.LockAnimationDuration

Review URL: https://codereview.chromium.org/82573002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238212 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238212