Added the CEA-708 support to the open-source project.

Issue: #1807

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=144726542

library/src/main/java/com/google/android/exoplayer2/text/SubtitleDecoderFactory.java

@@ -17,6 +17,7 @@
 
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.text.cea.Cea608Decoder;
+import com.google.android.exoplayer2.text.cea.Cea708Decoder;
 import com.google.android.exoplayer2.text.subrip.SubripDecoder;
 import com.google.android.exoplayer2.text.ttml.TtmlDecoder;
 import com.google.android.exoplayer2.text.tx3g.Tx3gDecoder;
@@ -58,6 +59,7 @@ public interface SubtitleDecoderFactory {
    * <li>SubRip ({@link SubripDecoder})</li>
    * <li>TX3G ({@link Tx3gDecoder})</li>
    * <li>Cea608 ({@link Cea608Decoder})</li>
+   * <li>Cea708 ({@link Cea708Decoder})</li>
    * </ul>
    */
   SubtitleDecoderFactory DEFAULT = new SubtitleDecoderFactory() {
@@ -78,6 +80,9 @@ public SubtitleDecoder createDecoder(Format format) {
             || format.sampleMimeType.equals(MimeTypes.APPLICATION_MP4CEA608)) {
           return clazz.asSubclass(SubtitleDecoder.class).getConstructor(String.class, Integer.TYPE)
               .newInstance(format.sampleMimeType, format.accessibilityChannel);
+        } else if (format.sampleMimeType.equals(MimeTypes.APPLICATION_CEA708)) {
+          return clazz.asSubclass(SubtitleDecoder.class).getConstructor(Integer.TYPE)
+              .newInstance(format.accessibilityChannel);
         } else {
           return clazz.asSubclass(SubtitleDecoder.class).getConstructor().newInstance();
         }
@@ -105,6 +110,8 @@ private Class<?> getDecoderClass(String mimeType) {
           case MimeTypes.APPLICATION_CEA608:
           case MimeTypes.APPLICATION_MP4CEA608:
             return Class.forName("com.google.android.exoplayer2.text.cea.Cea608Decoder");
+          case MimeTypes.APPLICATION_CEA708:
+            return Class.forName("com.google.android.exoplayer2.text.cea.Cea708Decoder");
           default:
             return null;
         }

library/src/main/java/com/google/android/exoplayer2/text/cea/Cea708Cue.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.text.cea;
+
+import android.text.Layout.Alignment;
+import com.google.android.exoplayer2.text.Cue;
+
+/**
+ * A {@link Cue} for CEA-708.
+ */
+/* package */ final class Cea708Cue extends Cue implements Comparable<Cea708Cue> {
+
+  /**
+   * An unset priority.
+   */
+  public static final int PRIORITY_UNSET = -1;
+
+  /**
+   * The priority of the cue box.
+   */
+  public final int priority;
+
+  /**
+   * @param text See {@link #text}.
+   * @param textAlignment See {@link #textAlignment}.
+   * @param line See {@link #line}.
+   * @param lineType See {@link #lineType}.
+   * @param lineAnchor See {@link #lineAnchor}.
+   * @param position See {@link #position}.
+   * @param positionAnchor See {@link #positionAnchor}.
+   * @param size See {@link #size}.
+   * @param windowColorSet See {@link #windowColorSet}.
+   * @param windowColor See {@link #windowColor}.
+   * @param priority See (@link #priority}.
+   */
+  public Cea708Cue(CharSequence text, Alignment textAlignment, float line, @LineType int lineType,
+      @AnchorType int lineAnchor, float position, @AnchorType int positionAnchor, float size,
+      boolean windowColorSet, int windowColor, int priority) {
+    super(text, textAlignment, line, lineType, lineAnchor, position, positionAnchor, size,
+        windowColorSet, windowColor);
+    this.priority = priority;
+  }
+
+  @Override
+  public int compareTo(Cea708Cue other) {
+    if (other.priority < priority) {
+      return -1;
+    } else if (other.priority > priority) {
+      return 1;
+    }
+    return 0;
+  }
+
+}