ash: Remove old lock animation implementation.

This deletes the SessionStateControllerImpl class (formerly
used when the --ash-disable-new-lock-animations flag, which
I'm also removing, was set) and moves
LockStateControllerImpl2 into LockStateController (which was
formerly an interface).

BUG=294310

Review URL: https://codereview.chromium.org/24980006

git-svn-id: http://src.chromium.org/svn/trunk/src/build@226298 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

ios/grit_whitelist.txt

@@ -420,8 +420,6 @@ IDS_FLAGS_ASH_DISABLE_PER_APP_LAUNCHER_DESCRIPTION
 IDS_FLAGS_ASH_DISABLE_PER_APP_LAUNCHER_NAME
 IDS_FLAGS_ASH_IMMERSIVE_FULLSCREEN_DESCRIPTION
 IDS_FLAGS_ASH_IMMERSIVE_FULLSCREEN_NAME
-IDS_FLAGS_ASH_NEW_LOCK_ANIMATIONS
-IDS_FLAGS_ASH_NEW_LOCK_ANIMATIONS_DESCRIPTION
 IDS_FLAGS_CAPTIVE_PORTAL_DETECTOR_DESCRIPTION
 IDS_FLAGS_CAPTIVE_PORTAL_DETECTOR_NAME
 IDS_FLAGS_CHROME_CAPTIVE_PORTAL_DETECTOR