Make SegmentDownloadAction constructor keys parameter simpler

Removed option to pass null keys parameter.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=185134822

library/core/src/main/java/com/google/android/exoplayer2/offline/SegmentDownloadAction.java

@@ -40,16 +40,11 @@ public abstract class SegmentDownloadAction<K> extends DownloadAction {
     public DownloadAction readFromStream(int version, DataInputStream input) throws IOException {
       Uri manifestUri = Uri.parse(input.readUTF());
       String data = input.readUTF();
+      boolean removeAction = input.readBoolean();
       int keyCount = input.readInt();
-      boolean removeAction = keyCount == -1;
+      K[] keys = createKeyArray(keyCount);
-      K[] keys;
+      for (int i = 0; i < keyCount; i++) {
-      if (removeAction) {
+        keys[i] = readKey(input);
-        keys = null;
-      } else {
-        keys = createKeyArray(keyCount);
-        for (int i = 0; i < keyCount; i++) {
-          keys[i] = readKey(input);
-        }
       }
       return createDownloadAction(manifestUri, removeAction, data, keys);
     }
@@ -74,12 +69,15 @@ public abstract class SegmentDownloadAction<K> extends DownloadAction {
    * @param manifestUri The {@link Uri} of the manifest to be downloaded.
    * @param removeAction Whether the data will be removed. If {@code false} it will be downloaded.
    * @param data Optional custom data for this action. If null, an empty string is used.
-   * @param keys Keys of representations to be downloaded. If empty or null, all representations are
+   * @param keys Keys of representations to be downloaded. If empty, all representations are
-   *     downloaded. If {@code removeAction} is true, this is ignored.
+   *     downloaded. If {@code removeAction} is true, {@code keys} should be an empty array.
    */
   protected SegmentDownloadAction(Uri manifestUri, boolean removeAction, String data, K[] keys) {
     super(data);
-    Assertions.checkArgument(!removeAction || keys == null || keys.length == 0);
+    Assertions.checkNotNull(keys);
+    if (removeAction) {
+      Assertions.checkArgument(keys.length == 0);
+    }
     this.manifestUri = manifestUri;
     this.keys = keys;
     this.removeAction = removeAction;
@@ -94,13 +92,10 @@ public abstract class SegmentDownloadAction<K> extends DownloadAction {
   public final void writeToStream(DataOutputStream output) throws IOException {
     output.writeUTF(manifestUri.toString());
     output.writeUTF(getData());
-    if (isRemoveAction()) {
+    output.writeBoolean(removeAction);
-      output.writeInt(-1);
+    output.writeInt(keys.length);
-    } else {
+    for (K key : keys) {
-      output.writeInt(keys.length);
+      writeKey(output, key);
-      for (K key : keys) {
-        writeKey(output, key);
-      }
     }
   }
 
@@ -124,11 +119,9 @@ public abstract class SegmentDownloadAction<K> extends DownloadAction {
     }
     SegmentDownloadAction<?> that = (SegmentDownloadAction<?>) o;
     return manifestUri.equals(that.manifestUri)
-        && (keys == null || keys.length == 0
+        && removeAction == that.removeAction
-            ? (that.keys == null || that.keys.length == 0)
+        && keys.length == that.keys.length
-            : (that.keys != null
+        && Arrays.asList(keys).containsAll(Arrays.asList(that.keys));
-                && that.keys.length == keys.length
-                && Arrays.asList(keys).containsAll(Arrays.asList(that.keys))));
   }
 
   @Override

library/core/src/main/java/com/google/android/exoplayer2/offline/SegmentDownloader.java

@@ -101,10 +101,10 @@ public abstract class SegmentDownloader<M, K> implements Downloader {
 
   /**
    * Selects multiple representations pointed to by the keys for downloading, checking status. Any
-   * previous selection is cleared. If keys are null or empty, all representations are downloaded.
+   * previous selection is cleared. If keys array is empty, all representations are downloaded.
    */
   public final void selectRepresentations(K[] keys) {
-    this.keys = (keys != null && keys.length > 0) ? keys.clone() : null;
+    this.keys = keys.length > 0 ? keys.clone() : null;
     resetCounters();
   }
 

library/dash/src/androidTest/java/com/google/android/exoplayer2/source/dash/offline/DashDownloaderTest.java

@@ -184,11 +184,6 @@ public class DashDownloaderTest extends InstrumentationTestCase {
     // select something random
     dashDownloader.selectRepresentations(new RepresentationKey[] {new RepresentationKey(0, 0, 0)});
     // clear selection
-    dashDownloader.selectRepresentations(null);
-    dashDownloader.download(null);
-    assertCachedData(cache, fakeDataSet);
-    dashDownloader.remove();
-
     dashDownloader.selectRepresentations(new RepresentationKey[0]);
     dashDownloader.download(null);
     assertCachedData(cache, fakeDataSet);

library/hls/src/androidTest/java/com/google/android/exoplayer2/source/hls/offline/HlsDownloaderTest.java

@@ -156,11 +156,6 @@ public class HlsDownloaderTest extends InstrumentationTestCase {
     // select something random
     hlsDownloader.selectRepresentations(new String[] {MEDIA_PLAYLIST_1_URI});
     // clear selection
-    hlsDownloader.selectRepresentations(null);
-    hlsDownloader.download(null);
-    assertCachedData(cache, fakeDataSet);
-    hlsDownloader.remove();
-
     hlsDownloader.selectRepresentations(new String[0]);
     hlsDownloader.download(null);
     assertCachedData(cache, fakeDataSet);