Document ChunkSampleSource constructors.

Issue: #1030
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=109674800

library/src/main/java/com/google/android/exoplayer/chunk/ChunkSampleSource.java

@@ -89,11 +89,25 @@ public class ChunkSampleSource implements SampleSource, SampleSourceReader, Load
   private MediaFormat downstreamMediaFormat;
   private Format downstreamFormat;
 
+  /**
+   * @param chunkSource A {@link ChunkSource} from which chunks to load are obtained.
+   * @param loadControl Controls when the source is permitted to load data.
+   * @param bufferSizeContribution The contribution of this source to the media buffer, in bytes.
+   */
   public ChunkSampleSource(ChunkSource chunkSource, LoadControl loadControl,
       int bufferSizeContribution) {
     this(chunkSource, loadControl, bufferSizeContribution, null, null, 0);
   }
 
+  /**
+   * @param chunkSource A {@link ChunkSource} from which chunks to load are obtained.
+   * @param loadControl Controls when the source is permitted to load data.
+   * @param bufferSizeContribution The contribution of this source to the media buffer, in bytes.
+   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
+   *     null if delivery of events is not required.
+   * @param eventListener A listener of events. May be null if delivery of events is not required.
+   * @param eventSourceId An identifier that gets passed to {@code eventListener} methods.
+   */
   public ChunkSampleSource(ChunkSource chunkSource, LoadControl loadControl,
       int bufferSizeContribution, Handler eventHandler, EventListener eventListener,
       int eventSourceId) {
@@ -101,6 +115,17 @@ public class ChunkSampleSource implements SampleSource, SampleSourceReader, Load
         eventSourceId, DEFAULT_MIN_LOADABLE_RETRY_COUNT);
   }
 
+  /**
+   * @param chunkSource A {@link ChunkSource} from which chunks to load are obtained.
+   * @param loadControl Controls when the source is permitted to load data.
+   * @param bufferSizeContribution The contribution of this source to the media buffer, in bytes.
+   * @param eventHandler A handler to use when delivering events to {@code eventListener}. May be
+   *     null if delivery of events is not required.
+   * @param eventListener A listener of events. May be null if delivery of events is not required.
+   * @param eventSourceId An identifier that gets passed to {@code eventListener} methods.
+   * @param minLoadableRetryCount The minimum number of times that the source should retry a load
+   *     before propagating an error.
+   */
   public ChunkSampleSource(ChunkSource chunkSource, LoadControl loadControl,
       int bufferSizeContribution, Handler eventHandler, EventListener eventListener,
       int eventSourceId, int minLoadableRetryCount) {