Fixes early transiton to Player.STATE_ENDED with MPD transition dyn…

…amic to static

This checkin fixes Issue androidx#1441 where the player transitons to `Player.STATE_ENDED` once
the buffer runs out on a DASH start-over playlist that has transitioned from dynamic to static.

The fix detects the DASH Period has changed offset to the window, which occurs when the
origin vendor follows the DASH-IF recommendations in
*Section 4.6.4. Transition Phase between Live and On-Demand* ,  summerized as:

-	adds the attribute `MPD@mediaPresentationDuration`
-	removes the attribute `MPD@minimumUpdatePeriod`
-	`Period@start` is removed (if it was present)
-	`Period@duration` is added (in case more than 1 period is present)
-	`Adaptationset .SegmentTemplate@presentationTimeOffset` is set to earliest presentation time of a segment in the Adaptationset

The MPD change does not affect the render position or the segment timeline at all, however
the cleanest way to implement this was to report a `PositionUpdateForPlaylistChange`
which triggers a seek and flushes the current buffered content.

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ExoPlayerImplInternal.java

@@ -3030,6 +3030,11 @@ private static PositionUpdateForPlaylistChange resolvePositionForPlaylistChange(
       }
     }
 
+    long periodPositionDeltaUs = checkPlayingPeriodPositionChanged(timeline, playbackInfo, period.windowIndex);
+    if (periodPositionDeltaUs > 0) {
+      periodPositionUs = periodPositionUs - periodPositionDeltaUs;
+    }
+
     return new PositionUpdateForPlaylistChange(
         newPeriodId,
         periodPositionUs,
@@ -3039,6 +3044,22 @@ private static PositionUpdateForPlaylistChange resolvePositionForPlaylistChange(
         setTargetLiveOffset);
   }
 
+  private static long checkPlayingPeriodPositionChanged(Timeline timeline, PlaybackInfo playbackInfo, int currentWindowIndex) {
+    long periodPositionDeltaUs = C.TIME_UNSET;
+    if (!playbackInfo.timeline.isEmpty() && !timeline.isEmpty() && !playbackInfo.periodId.isAd()) {
+      Timeline.Window newWindow = timeline.getWindow(currentWindowIndex, new Timeline.Window());
+      Timeline.Window oldWindow = playbackInfo.timeline.getWindow(currentWindowIndex, new Timeline.Window());
+      if (oldWindow.isDynamic && ! newWindow.isDynamic) {
+        Timeline.Period newPeriod = timeline.getPeriodByUid(playbackInfo.periodId.periodUid, new Timeline.Period());
+        int windowIndex = newPeriod.windowIndex;
+        Pair<Object, Long> oldPositionZero = playbackInfo.timeline.getPeriodPosition(oldWindow, new Timeline.Period(), windowIndex, 0);
+        Pair<Object, Long> newPositionZero = timeline.getPeriodPosition(newWindow, new Timeline.Period(), windowIndex, 0);
+        periodPositionDeltaUs = oldPositionZero.second - newPositionZero.second;
+      }
+    }
+    return periodPositionDeltaUs;
+  }
+
   private static boolean isIgnorableServerSideAdInsertionPeriodChange(
       boolean isUsingPlaceholderPeriod,
       MediaPeriodId oldPeriodId,