Improve @IntDef inside Selection

This patch is aligning various @IntDef to some standard used with many other CLs:

1. @IntDef is first, @Retention second and related @interface third
2. there is used @Retention(RetentionPolicy.SOURCE)
3. @IntDef entries are inside @interface

BUG=919666

Change-Id: I2d9f057071bfa282809545a91d6917908e1594f5
Reviewed-on: https://chromium-review.googlesource.com/c/1480371
Reviewed-by: Pedro Amaral <amaralp@chromium.org>
Commit-Queue: Marcin Wiącek <marcin@mwiacek.com>
Cr-Commit-Position: refs/heads/master@{#636566}
3 files changed