Restructure media period queue tracker in AnalyticsCollector.

The current structure tries to associate events to media periods and windows
based on the reported values and the current timeline. However the reported
EventTime may not always be consistent in case the timeline doesn't contain
windows or media periods yet or not anymore.

The recent changes to MediaPeriodId allow to use it as a unique identifer for
media periods independent of the timeline. This enables more accurate tracking
of the media period queue and prevents reporting events with inconsistent
data.

Issue:#4492
Issue:#4634

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=210713120

RELEASENOTES.md

@@ -133,6 +133,9 @@
 * Provide additional information for adaptive track selection.
   `TrackSelection.updateSelectedTrack` has two new parameters for the current
   queue of media chunks and iterators for information about upcoming chunks.
+* Prevent potential issues when reporting events for multi-period media sources
+  ([#4492](https://github.com/google/ExoPlayer/issues/4492) and
+  [#4634](https://github.com/google/ExoPlayer/issues/4634)).
 
 ### 2.8.4 ###
 

library/core/src/test/java/com/google/android/exoplayer2/analytics/AnalyticsCollectorTest.java

@@ -619,7 +619,7 @@ public final class AnalyticsCollectorTest {
         .containsExactly(window0Period1Seq0, window1Period0Seq1);
     assertThat(listener.getEvents(EVENT_MEDIA_PERIOD_CREATED))
         .containsExactly(window0Period1Seq0, window1Period0Seq1);
-    assertThat(listener.getEvents(EVENT_MEDIA_PERIOD_RELEASED)).containsExactly(period0Seq1);
+    assertThat(listener.getEvents(EVENT_MEDIA_PERIOD_RELEASED)).containsExactly(window1Period0Seq1);
     assertThat(listener.getEvents(EVENT_READING_STARTED))
         .containsExactly(window0Period1Seq0, window1Period0Seq1);
     assertThat(listener.getEvents(EVENT_DECODER_ENABLED))