Migrate Orientation to the @IntDef

@IntDef/@StringDef annotation are preferred way for declaring
set of String/int values

1. they need less space in APK than enum, see
2. they give more control over allowed values than "static final" values

Main goal of patch is writing @Orientation interface in the form common with Chrome @IntDef:

1. with @IntDef first, @Retention second
   and related @interface third
2. with values inside @interface
3. with @Retention(RetentionPolicy.SOURCE)
4. without "static final" in the @interface


Change-Id: I6e96496eedf82253687c287ea7a70b3c92f63ace
Reviewed-on: https://chromium-review.googlesource.com/c/1480450
Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Marcin Wiącek <marcin@mwiacek.com>
Cr-Commit-Position: refs/heads/master@{#634876}
7 files changed