Remove getLoadedData API from ExoPlayer components.

This API wasn't particularly nice. Best to remove it whilst
hopefully no-one is using it. Leaving the ReadHead abstraction
in place, since it might well prove useful in the future.

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

@@ -135,18 +135,6 @@ public abstract class Chunk implements Loadable {
   }
 
   /**
-   * Returns a byte array containing the loaded data. If the chunk is partially loaded, this
-   * method returns the data that has been loaded so far. If nothing has been loaded, null is
-   * returned.
-   *
-   * @return The loaded data or null.
-   */
-  public final byte[] getLoadedData() {
-    Assertions.checkState(dataSourceStream != null);
-    return dataSourceStream.getLoadedData();
-  }
-
-  /**
    * Invoked by {@link #consume()}. Implementations may override this method if they wish to
    * consume the loaded data at this point.
    * <p>

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

@@ -64,10 +64,8 @@ public class SingleSampleMediaChunk extends MediaChunk {
    * @param nextChunkIndex The index of the next chunk, or -1 if this is the last chunk.
    * @param sampleFormat The format of the media contained by the chunk.
    * @param headerData Custom header data for the sample. May be null. If set, the header data is
-   *     prepended to the sample data returned when {@link #read(SampleHolder)} is called. It is
-   *     however not considered part of the loaded data, and so is not prepended to the data
-   *     returned by {@link #getLoadedData()}. It is also not reflected in the values returned by
-   *     {@link #bytesLoaded()} and {@link #getLength()}.
+   *     prepended to the sample data returned when {@link #read(SampleHolder)} is called. It is not
+   *     reflected in the values returned by {@link #bytesLoaded()} and {@link #getLength()}.
    */
   public SingleSampleMediaChunk(DataSource dataSource, DataSpec dataSpec, Format format,
       int trigger, long startTimeUs, long endTimeUs, int nextChunkIndex, MediaFormat sampleFormat,

library/src/main/java/com/google/android/exoplayer/upstream/DataSourceStream.java

@@ -119,26 +119,6 @@ public final class DataSourceStream implements Loadable, NonBlockingInputStream
     return resolvedLength != C.LENGTH_UNBOUNDED && loadPosition == resolvedLength;
   }
 
-  /**
-   * Returns a byte array containing the loaded data. If the data is partially loaded, this method
-   * returns the portion of the data that has been loaded so far. If nothing has been loaded, null
-   * is returned. This method does not use or update the current read position.
-   * <p>
-   * Note: The read methods provide a more efficient way of consuming the loaded data. Use this
-   * method only when a freshly allocated byte[] containing all of the loaded data is required.
-   *
-   * @return The loaded data, or null.
-   */
-  public final byte[] getLoadedData() {
-    if (loadPosition == 0) {
-      return null;
-    }
-
-    byte[] rawData = new byte[(int) loadPosition];
-    read(null, rawData, 0, new ReadHead(), rawData.length);
-    return rawData;
-  }
-
   // {@link NonBlockingInputStream} implementation.
 
   @Override