Fix single sample loading + seeking in HLS.

Issue #587

library/src/main/java/com/google/android/exoplayer/MediaFormat.java

@@ -138,6 +138,12 @@ public final class MediaFormat {
         maxHeight);
   }
 
+  public MediaFormat copyWithDurationUs(long durationUs) {
+    return new MediaFormat(mimeType, maxInputSize, durationUs, width, height, rotationDegrees,
+        pixelWidthHeightRatio, channelCount, sampleRate, language, initializationData, maxWidth,
+        maxHeight);
+  }
+
   /**
    * @return A {@link MediaFormat} representation of this format.
    */

library/src/main/java/com/google/android/exoplayer/SingleSampleSource.java

@@ -176,7 +176,7 @@ public final class SingleSampleSource implements SampleSource, SampleSourceReade
   // Private methods.
 
   private void maybeStartLoading() {
-    if (loadingFinished || state != STATE_END_OF_STREAM || loader.isLoading()) {
+    if (loadingFinished || state == STATE_END_OF_STREAM || loader.isLoading()) {
       return;
     }
     if (currentLoadableException != null) {

library/src/main/java/com/google/android/exoplayer/hls/HlsSampleSource.java

@@ -136,7 +136,8 @@ public final class HlsSampleSource implements SampleSource, SampleSourceReader,
         downstreamMediaFormats = new MediaFormat[trackCount];
         mediaFormats = new MediaFormat[trackCount];
         for (int i = 0; i < trackCount; i++) {
-          mediaFormats[i] = extractor.getMediaFormat(i);
+          mediaFormats[i] = extractor.getMediaFormat(i).copyWithDurationUs(
+              chunkSource.getDurationUs());
         }
         prepared = true;
         return true;