onPlayerStateChanged is not consistent for multiple listeners

[fcapinho]

Issue description

State updates from Player.EventListener.onPlayerStateChanged() may be inconsistent between multiple listeners added with Player.addListener(). This happens when one of the listeners callbacks changes the Player state.

For example, if a listener call Player.stop() when receiving a Player.STATE_ENDED state update, all succeeding listeners will receive a Player.STATE_IDLE state update.
The Expected behaviour is that all listeners receive the same state update values.

Reproduction steps

1. Apply this patch to the main demo app in order to add two new Player.EventListener:
2. Play any video from the main demo app. The following logcat snippet is from full play of "YouTube DASH -> Google Play (WebM, VP9)":

05-21 01:16:58.016 16603-16603/com.google.android.exoplayer2.demo D/PlayerEndEventListener: playbackState: IDLE / playyWhenReady: true
05-21 01:16:58.017 16603-16603/com.google.android.exoplayer2.demo D/PlayerLogEventListener: playbackState: IDLE / playyWhenReady: true
05-21 01:16:58.208 16603-16603/com.google.android.exoplayer2.demo D/PlayerEndEventListener: playbackState: BUFFERING / playyWhenReady: true
05-21 01:16:58.208 16603-16603/com.google.android.exoplayer2.demo D/PlayerLogEventListener: playbackState: BUFFERING / playyWhenReady: true
05-21 01:17:00.643 16603-16603/com.google.android.exoplayer2.demo D/PlayerEndEventListener: playbackState: READY / playyWhenReady: true
05-21 01:17:00.643 16603-16603/com.google.android.exoplayer2.demo D/PlayerLogEventListener: playbackState: READY / playyWhenReady: true
05-21 01:18:01.904 16603-16603/com.google.android.exoplayer2.demo D/PlayerEndEventListener: playbackState: ENDED / playyWhenReady: true
05-21 01:18:01.905 16603-16603/com.google.android.exoplayer2.demo D/PlayerEndEventListener: playbackState: IDLE / playyWhenReady: true
05-21 01:18:01.905 16603-16603/com.google.android.exoplayer2.demo D/PlayerLogEventListener: playbackState: IDLE / playyWhenReady: true
05-21 01:18:01.921 16603-16603/com.google.android.exoplayer2.demo D/PlayerLogEventListener: playbackState: IDLE / playyWhenReady: true

The issue is on the latest 4 state updates. Note that PlayerLogEventListener never receives the Player.STATE_ENDED state upate:

PlayerEndEventListener: playbackState: ENDED
PlayerEndEventListener: playbackState: IDLE
PlayerLogEventListener: playbackState: IDLE
PlayerLogEventListener: playbackState: IDLE

Link to test content

Can be reproduced with all medias from main demo app.

Version of ExoPlayer being used

r2.8.0

Device(s) and version(s) of Android being used

Reproduced on Galaxy S7 and Motorola G5, both running Android 7.0 (API 24), and on Emulator running Android 8.1.0 (API 27).

A full bug report captured from the device

bugreport-sdk_gphone_x86-OSM1.180201.007-2018-05-21-01-54-13.zip

[tonihei]

We are aware of this issue and already have plans to fix this. Marking as bug until it's fixed.