Scale the minimum buffer size in shouldContinueLoading

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=191885689

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

@@ -301,6 +301,14 @@ public class DefaultLoadControl implements LoadControl {
   public boolean shouldContinueLoading(long bufferedDurationUs, float playbackSpeed) {
   public boolean shouldContinueLoading(long bufferedDurationUs, float playbackSpeed) {
     boolean targetBufferSizeReached = allocator.getTotalBytesAllocated() >= targetBufferSize;
     boolean targetBufferSizeReached = allocator.getTotalBytesAllocated() >= targetBufferSize;
     boolean wasBuffering = isBuffering;
     boolean wasBuffering = isBuffering;
+    long minBufferUs = this.minBufferUs;
+    if (playbackSpeed > 1) {
+      // The playback speed is faster than real time, so scale up the minimum required media
+      // duration to keep enough media buffered for a playout duration of minBufferUs.
+      long mediaDurationMinBufferUs =
+          Util.getMediaDurationForPlayoutDuration(minBufferUs, playbackSpeed);
+      minBufferUs = Math.min(mediaDurationMinBufferUs, maxBufferUs);
+    }
     if (bufferedDurationUs < minBufferUs) {
     if (bufferedDurationUs < minBufferUs) {
       isBuffering = prioritizeTimeOverSizeThresholds || !targetBufferSizeReached;
       isBuffering = prioritizeTimeOverSizeThresholds || !targetBufferSizeReached;
     } else if (bufferedDurationUs > maxBufferUs || targetBufferSizeReached) {
     } else if (bufferedDurationUs > maxBufferUs || targetBufferSizeReached) {

library/core/src/test/java/com/google/android/exoplayer2/DefaultLoadControlTest.java

@@ -86,6 +86,25 @@ public class DefaultLoadControlTest {
   }
   }
 
 
   @Test
   @Test
+  public void testShouldContinueLoadingWithMinBufferReached_inFastPlayback() {
+    createDefaultLoadControl();
+
+    // At normal playback speed, we stop buffering when the buffer reaches the minimum.
+    assertThat(loadControl.shouldContinueLoading(MIN_BUFFER_US, SPEED)).isFalse();
+
+    // At double playback speed, we continue loading.
+    assertThat(loadControl.shouldContinueLoading(MIN_BUFFER_US, /* playbackSpeed= */ 2f)).isTrue();
+  }
+
+  @Test
+  public void testShouldNotContinueLoadingWithMaxBufferReached_inFastPlayback() {
+    createDefaultLoadControl();
+
+    assertThat(loadControl.shouldContinueLoading(MAX_BUFFER_US + 1, /* playbackSpeed= */ 100f))
+        .isFalse();
+  }
+
+  @Test
   public void testStartsPlayback_whenMinBufferSizeReached() {
   public void testStartsPlayback_whenMinBufferSizeReached() {
     createDefaultLoadControl();
     createDefaultLoadControl();
     assertThat(loadControl.shouldStartPlayback(MIN_BUFFER_US, SPEED, /* rebuffering= */ false))
     assertThat(loadControl.shouldStartPlayback(MIN_BUFFER_US, SPEED, /* rebuffering= */ false))