Some minor cleanup related to track selection and caching

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=155103828

demo/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -261,10 +261,10 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
       DefaultRenderersFactory renderersFactory = new DefaultRenderersFactory(this,
       DefaultRenderersFactory renderersFactory = new DefaultRenderersFactory(this,
           drmSessionManager, extensionRendererMode);
           drmSessionManager, extensionRendererMode);
 
 
-      TrackSelection.Factory videoTrackSelectionFactory =
+      TrackSelection.Factory adaptiveTrackSelectionFactory =
           new AdaptiveTrackSelection.Factory(BANDWIDTH_METER);
           new AdaptiveTrackSelection.Factory(BANDWIDTH_METER);
-      trackSelector = new DefaultTrackSelector(videoTrackSelectionFactory);
-      trackSelectionHelper = new TrackSelectionHelper(trackSelector, videoTrackSelectionFactory);
+      trackSelector = new DefaultTrackSelector(adaptiveTrackSelectionFactory);
+      trackSelectionHelper = new TrackSelectionHelper(trackSelector, adaptiveTrackSelectionFactory);
       lastSeenTrackGroupArray = null;
       lastSeenTrackGroupArray = null;
 
 
       player = ExoPlayerFactory.newSimpleInstance(renderersFactory, trackSelector);
       player = ExoPlayerFactory.newSimpleInstance(renderersFactory, trackSelector);

library/core/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java

@@ -24,6 +24,7 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.RendererCapabilities;
 import com.google.android.exoplayer2.RendererCapabilities;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.source.TrackGroupArray;
+import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Util;
 import com.google.android.exoplayer2.util.Util;
 import java.util.ArrayList;
 import java.util.ArrayList;
@@ -376,10 +377,21 @@ public class DefaultTrackSelector extends MappingTrackSelector {
   private final AtomicReference<Parameters> paramsReference;
   private final AtomicReference<Parameters> paramsReference;
 
 
   /**
   /**
-   * Constructs an instance that does not support adaptive tracks.
+   * Constructs an instance that does not support adaptive track selection.
    */
    */
   public DefaultTrackSelector() {
   public DefaultTrackSelector() {
-    this(null);
+    this((TrackSelection.Factory) null);
+  }
+
+  /**
+   * Constructs an instance that supports adaptive track selection. Adaptive track selections use
+   * the provided {@link BandwidthMeter} to determine which individual track should be used during
+   * playback.
+   *
+   * @param bandwidthMeter The {@link BandwidthMeter}.
+   */
+  public DefaultTrackSelector(BandwidthMeter bandwidthMeter) {
+    this(new AdaptiveTrackSelection.Factory(bandwidthMeter));
   }
   }
 
 
   /**
   /**

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheDataSource.java

@@ -54,8 +54,8 @@ public final class CacheDataSource implements DataSource {
       FLAG_IGNORE_CACHE_FOR_UNSET_LENGTH_REQUESTS})
       FLAG_IGNORE_CACHE_FOR_UNSET_LENGTH_REQUESTS})
   public @interface Flags {}
   public @interface Flags {}
   /**
   /**
-   * A flag indicating whether we will block reads if the cache key is locked. If this flag is
-   * set, then we will read from upstream if the cache key is locked.
+   * A flag indicating whether we will block reads if the cache key is locked. If unset then data is
+   * read from upstream if the cache key is locked, regardless of whether the data is cached.
    */
    */
   public static final int FLAG_BLOCK_ON_CACHE = 1 << 0;
   public static final int FLAG_BLOCK_ON_CACHE = 1 << 0;
 
 
@@ -110,7 +110,23 @@ public final class CacheDataSource implements DataSource {
 
 
   /**
   /**
    * Constructs an instance with default {@link DataSource} and {@link DataSink} instances for
    * Constructs an instance with default {@link DataSource} and {@link DataSink} instances for
-   * reading and writing the cache and with {@link #DEFAULT_MAX_CACHE_FILE_SIZE}.
+   * reading and writing the cache.
+   *
+   * @param cache The cache.
+   * @param upstream A {@link DataSource} for reading data not in the cache.
+   */
+  public CacheDataSource(Cache cache, DataSource upstream) {
+    this(cache, upstream, 0, DEFAULT_MAX_CACHE_FILE_SIZE);
+  }
+
+  /**
+   * Constructs an instance with default {@link DataSource} and {@link DataSink} instances for
+   * reading and writing the cache.
+   *
+   * @param cache The cache.
+   * @param upstream A {@link DataSource} for reading data not in the cache.
+   * @param flags A combination of {@link #FLAG_BLOCK_ON_CACHE}, {@link #FLAG_IGNORE_CACHE_ON_ERROR}
+   *     and {@link #FLAG_IGNORE_CACHE_FOR_UNSET_LENGTH_REQUESTS}, or 0.
    */
    */
   public CacheDataSource(Cache cache, DataSource upstream, @Flags int flags) {
   public CacheDataSource(Cache cache, DataSource upstream, @Flags int flags) {
     this(cache, upstream, flags, DEFAULT_MAX_CACHE_FILE_SIZE);
     this(cache, upstream, flags, DEFAULT_MAX_CACHE_FILE_SIZE);
@@ -123,8 +139,8 @@ public final class CacheDataSource implements DataSource {
    *
    *
    * @param cache The cache.
    * @param cache The cache.
    * @param upstream A {@link DataSource} for reading data not in the cache.
    * @param upstream A {@link DataSource} for reading data not in the cache.
-   * @param flags A combination of {@link #FLAG_BLOCK_ON_CACHE} and {@link
-   *     #FLAG_IGNORE_CACHE_ON_ERROR} or 0.
+   * @param flags A combination of {@link #FLAG_BLOCK_ON_CACHE}, {@link #FLAG_IGNORE_CACHE_ON_ERROR}
+   *     and {@link #FLAG_IGNORE_CACHE_FOR_UNSET_LENGTH_REQUESTS}, or 0.
    * @param maxCacheFileSize The maximum size of a cache file, in bytes. If the cached data size
    * @param maxCacheFileSize The maximum size of a cache file, in bytes. If the cached data size
    *     exceeds this value, then the data will be fragmented into multiple cache files. The
    *     exceeds this value, then the data will be fragmented into multiple cache files. The
    *     finer-grained this is the finer-grained the eviction policy can be.
    *     finer-grained this is the finer-grained the eviction policy can be.
@@ -145,8 +161,8 @@ public final class CacheDataSource implements DataSource {
    * @param cacheReadDataSource A {@link DataSource} for reading data from the cache.
    * @param cacheReadDataSource A {@link DataSource} for reading data from the cache.
    * @param cacheWriteDataSink A {@link DataSink} for writing data to the cache. If null, cache is
    * @param cacheWriteDataSink A {@link DataSink} for writing data to the cache. If null, cache is
    *     accessed read-only.
    *     accessed read-only.
-   * @param flags A combination of {@link #FLAG_BLOCK_ON_CACHE} and {@link
-   *     #FLAG_IGNORE_CACHE_ON_ERROR} or 0.
+   * @param flags A combination of {@link #FLAG_BLOCK_ON_CACHE}, {@link #FLAG_IGNORE_CACHE_ON_ERROR}
+   *     and {@link #FLAG_IGNORE_CACHE_FOR_UNSET_LENGTH_REQUESTS}, or 0.
    * @param eventListener An optional {@link EventListener} to receive events.
    * @param eventListener An optional {@link EventListener} to receive events.
    */
    */
   public CacheDataSource(Cache cache, DataSource upstream, DataSource cacheReadDataSource,
   public CacheDataSource(Cache cache, DataSource upstream, DataSource cacheReadDataSource,

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheDataSourceFactory.java

@@ -34,17 +34,25 @@ public final class CacheDataSourceFactory implements DataSource.Factory {
   private final EventListener eventListener;
   private final EventListener eventListener;
 
 
   /**
   /**
+   * @see CacheDataSource#CacheDataSource(Cache, DataSource)
+   */
+  public CacheDataSourceFactory(Cache cache, DataSource.Factory upstreamFactory) {
+    this(cache, upstreamFactory, 0);
+  }
+
+  /**
    * @see CacheDataSource#CacheDataSource(Cache, DataSource, int)
    * @see CacheDataSource#CacheDataSource(Cache, DataSource, int)
    */
    */
-  public CacheDataSourceFactory(Cache cache, DataSource.Factory upstreamFactory, int flags) {
+  public CacheDataSourceFactory(Cache cache, DataSource.Factory upstreamFactory,
+      @CacheDataSource.Flags int flags) {
     this(cache, upstreamFactory, flags, CacheDataSource.DEFAULT_MAX_CACHE_FILE_SIZE);
     this(cache, upstreamFactory, flags, CacheDataSource.DEFAULT_MAX_CACHE_FILE_SIZE);
   }
   }
 
 
   /**
   /**
    * @see CacheDataSource#CacheDataSource(Cache, DataSource, int, long)
    * @see CacheDataSource#CacheDataSource(Cache, DataSource, int, long)
    */
    */
-  public CacheDataSourceFactory(Cache cache, DataSource.Factory upstreamFactory, int flags,
-      long maxCacheFileSize) {
+  public CacheDataSourceFactory(Cache cache, DataSource.Factory upstreamFactory,
+      @CacheDataSource.Flags int flags, long maxCacheFileSize) {
     this(cache, upstreamFactory, new FileDataSourceFactory(),
     this(cache, upstreamFactory, new FileDataSourceFactory(),
         new CacheDataSinkFactory(cache, maxCacheFileSize), flags, null);
         new CacheDataSinkFactory(cache, maxCacheFileSize), flags, null);
   }
   }
@@ -54,8 +62,8 @@ public final class CacheDataSourceFactory implements DataSource.Factory {
    *     EventListener)
    *     EventListener)
    */
    */
   public CacheDataSourceFactory(Cache cache, Factory upstreamFactory,
   public CacheDataSourceFactory(Cache cache, Factory upstreamFactory,
-      Factory cacheReadDataSourceFactory,
-      DataSink.Factory cacheWriteDataSinkFactory, int flags, EventListener eventListener) {
+      Factory cacheReadDataSourceFactory, DataSink.Factory cacheWriteDataSinkFactory,
+      @CacheDataSource.Flags int flags, EventListener eventListener) {
     this.cache = cache;
     this.cache = cache;
     this.upstreamFactory = upstreamFactory;
     this.upstreamFactory = upstreamFactory;
     this.cacheReadDataSourceFactory = cacheReadDataSourceFactory;
     this.cacheReadDataSourceFactory = cacheReadDataSourceFactory;