Fix two ad insertion related bugs in DefaultPlaybackSessionManager.

1. A content session after an ad has been played was not re-marked as active,
   leading to new ad session being marked as active too early.
2. Switching from content to post-roll ended the content session because
   the return value of getAdGroupTimeUs of C.TIME_END_OF_SOURCE was not
   handled. Using the nextAdGroupIndex instead.

PiperOrigin-RevId: 246977327

demos/main/build.gradle

@@ -63,7 +63,7 @@ android {
 
 dependencies {
     implementation 'androidx.annotation:annotation:1.0.2'
-    implementation 'androidx.legacy:legacy-support-core-ui:1.0.0'
+    implementation 'com.android.support:support-core-ui:' + supportLibraryVersion
     implementation 'androidx.fragment:fragment:1.0.0'
     implementation 'com.google.android.material:material:1.0.0'
     implementation project(modulePrefix + 'library-core')

demos/main/src/main/java/com/google/android/exoplayer2/demo/TrackSelectionDialog.java

@@ -25,7 +25,7 @@ import androidx.fragment.app.DialogFragment;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentPagerAdapter;
-import androidx.viewpager.widget.ViewPager;
+import android.support.v4.view.ViewPager;
 import androidx.appcompat.app.AppCompatDialog;
 import android.util.SparseArray;
 import android.view.LayoutInflater;

demos/main/src/main/res/layout/track_selection_dialog.xml

@@ -19,7 +19,7 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
-  <androidx.viewpager.widget.ViewPager
+  <android.support.v4.view.ViewPager
       android:id="@+id/track_selection_dialog_view_pager"
       android:layout_width="match_parent"
       android:layout_height="0dp"
@@ -32,7 +32,7 @@
         app:tabGravity="fill"
         app:tabMode="fixed"/>
 
-  </androidx.viewpager.widget.ViewPager>
+  </android.support.v4.view.ViewPager>
 
   <LinearLayout
       android:orientation="horizontal"

library/core/src/main/java/com/google/android/exoplayer2/Timeline.java

@@ -396,7 +396,8 @@ public abstract class Timeline {
      * microseconds.
      *
      * @param adGroupIndex The ad group index.
-     * @return The time of the ad group at the index, in microseconds.
+     * @return The time of the ad group at the index, in microseconds, or {@link
+     *     C#TIME_END_OF_SOURCE} for a post-roll ad group.
      */
     public long getAdGroupTimeUs(int adGroupIndex) {
       return adPlaybackState.adGroupTimesUs[adGroupIndex];

library/core/src/main/java/com/google/android/exoplayer2/analytics/DefaultPlaybackSessionManager.java

@@ -202,10 +202,12 @@ public final class DefaultPlaybackSessionManager implements PlaybackSessionManag
   @RequiresNonNull("listener")
   private void updateActiveSession(EventTime eventTime, SessionDescriptor sessionDescriptor) {
     currentMediaPeriodId = eventTime.mediaPeriodId;
-    if (sessionDescriptor.isCreated && !sessionDescriptor.isActive) {
+    if (sessionDescriptor.isCreated) {
-      sessionDescriptor.isActive = true;
       activeSessionId = sessionDescriptor.sessionId;
-      listener.onSessionActive(eventTime, sessionDescriptor.sessionId);
+      if (!sessionDescriptor.isActive) {
+        sessionDescriptor.isActive = true;
+        listener.onSessionActive(eventTime, sessionDescriptor.sessionId);
+      }
     }
   }
 
@@ -326,13 +328,9 @@ public final class DefaultPlaybackSessionManager implements PlaybackSessionManag
             || (eventAdGroup == adMediaPeriodId.adGroupIndex
                 && eventAdIndex > adMediaPeriodId.adIndexInAdGroup);
       } else {
-        eventTime.timeline.getPeriod(adPeriodIndex, period);
-        long adGroupTimeMs =
-            adMediaPeriodId.adGroupIndex < period.getAdGroupCount()
-                ? C.usToMs(period.getAdGroupTimeUs(adMediaPeriodId.adGroupIndex))
-                : 0;
         // Finished if the event is for content after this ad.
-        return adGroupTimeMs <= eventTime.currentPlaybackPositionMs;
+        return eventTime.mediaPeriodId.nextAdGroupIndex == C.INDEX_UNSET
+            || eventTime.mediaPeriodId.nextAdGroupIndex > adMediaPeriodId.adGroupIndex;
       }
     }
 

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

@@ -598,6 +598,43 @@ public final class DefaultPlaybackSessionManagerTest {
     assertThat(updatedSessionId300).isEqualTo(sessionId300);
   }
 
+  @Test
+  public void timelineUpdate_withContent_doesNotFinishFuturePostrollAd() {
+    Timeline adTimeline =
+        new FakeTimeline(
+            new TimelineWindowDefinition(
+                /* periodCount= */ 1,
+                /* id= */ 0,
+                /* isSeekable= */ true,
+                /* isDynamic= */ false,
+                /* durationUs =*/ 10 * C.MICROS_PER_SECOND,
+                new AdPlaybackState(/* adGroupTimesUs= */ C.TIME_END_OF_SOURCE)
+                    .withAdCount(/* adGroupIndex= */ 0, /* adCount= */ 1)));
+    EventTime adEventTime =
+        createEventTime(
+            adTimeline,
+            /* windowIndex= */ 0,
+            new MediaPeriodId(
+                adTimeline.getUidOfPeriod(/* periodIndex= */ 0),
+                /* adGroupIndex= */ 0,
+                /* adIndexInAdGroup= */ 0,
+                /* windowSequenceNumber= */ 0));
+    EventTime contentEventTime =
+        createEventTime(
+            adTimeline,
+            /* windowIndex= */ 0,
+            new MediaPeriodId(
+                adTimeline.getUidOfPeriod(/* periodIndex= */ 0),
+                /* windowSequenceNumber= */ 0,
+                /* nextAdGroupIndex= */ 0));
+    sessionManager.updateSessions(contentEventTime);
+    sessionManager.updateSessions(adEventTime);
+
+    sessionManager.handleTimelineUpdate(contentEventTime);
+
+    verify(mockListener, never()).onSessionFinished(any(), anyString(), anyBoolean());
+  }
+
   @Test
   public void positionDiscontinuity_withinWindow_doesNotFinishSession() {
     Timeline timeline =
@@ -943,6 +980,70 @@ public final class DefaultPlaybackSessionManagerTest {
     verifyNoMoreInteractions(mockListener);
   }
 
+  @Test
+  public void
+      updateSessions_withNewAd_afterDiscontinuitiesFromContentToAdAndBack_doesNotActivateNewAd() {
+    Timeline adTimeline =
+        new FakeTimeline(
+            new TimelineWindowDefinition(
+                /* periodCount= */ 1,
+                /* id= */ 0,
+                /* isSeekable= */ true,
+                /* isDynamic= */ false,
+                /* durationUs =*/ 10 * C.MICROS_PER_SECOND,
+                new AdPlaybackState(
+                        /* adGroupTimesUs= */ 2 * C.MICROS_PER_SECOND, 5 * C.MICROS_PER_SECOND)
+                    .withAdCount(/* adGroupIndex= */ 0, /* adCount= */ 1)
+                    .withAdCount(/* adGroupIndex= */ 1, /* adCount= */ 1)));
+    EventTime adEventTime1 =
+        createEventTime(
+            adTimeline,
+            /* windowIndex= */ 0,
+            new MediaPeriodId(
+                adTimeline.getUidOfPeriod(/* periodIndex= */ 0),
+                /* adGroupIndex= */ 0,
+                /* adIndexInAdGroup= */ 0,
+                /* windowSequenceNumber= */ 0));
+    EventTime adEventTime2 =
+        createEventTime(
+            adTimeline,
+            /* windowIndex= */ 0,
+            new MediaPeriodId(
+                adTimeline.getUidOfPeriod(/* periodIndex= */ 0),
+                /* adGroupIndex= */ 1,
+                /* adIndexInAdGroup= */ 0,
+                /* windowSequenceNumber= */ 0));
+    EventTime contentEventTime1 =
+        createEventTime(
+            adTimeline,
+            /* windowIndex= */ 0,
+            new MediaPeriodId(
+                adTimeline.getUidOfPeriod(/* periodIndex= */ 0),
+                /* windowSequenceNumber= */ 0,
+                /* nextAdGroupIndex= */ 0));
+    EventTime contentEventTime2 =
+        createEventTime(
+            adTimeline,
+            /* windowIndex= */ 0,
+            new MediaPeriodId(
+                adTimeline.getUidOfPeriod(/* periodIndex= */ 0),
+                /* windowSequenceNumber= */ 0,
+                /* nextAdGroupIndex= */ 1));
+    sessionManager.handleTimelineUpdate(contentEventTime1);
+    sessionManager.updateSessions(contentEventTime1);
+    sessionManager.updateSessions(adEventTime1);
+    sessionManager.handlePositionDiscontinuity(
+        adEventTime1, Player.DISCONTINUITY_REASON_AD_INSERTION);
+    sessionManager.handlePositionDiscontinuity(
+        contentEventTime2, Player.DISCONTINUITY_REASON_AD_INSERTION);
+    String adSessionId2 =
+        sessionManager.getSessionForMediaPeriodId(adTimeline, adEventTime2.mediaPeriodId);
+
+    sessionManager.updateSessions(adEventTime2);
+
+    verify(mockListener, never()).onSessionActive(any(), eq(adSessionId2));
+  }
+
   private static EventTime createEventTime(
       Timeline timeline, int windowIndex, @Nullable MediaPeriodId mediaPeriodId) {
     return new EventTime(