Don't read GaSpecificConfig unless required

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=164125579

library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/LatmReader.java

@@ -256,7 +256,7 @@ public final class LatmReader implements ElementaryStreamReader {
 
   private int parseAudioSpecificConfig(ParsableBitArray data) throws ParserException {
     int bitsLeft = data.bitsLeft();
-    Pair<Integer, Integer> config = CodecSpecificDataUtil.parseAacAudioSpecificConfig(data);
+    Pair<Integer, Integer> config = CodecSpecificDataUtil.parseAacAudioSpecificConfig(data, true);
     sampleRateHz = config.first;
     channelCount = config.second;
     return bitsLeft - data.bitsLeft();

library/core/src/main/java/com/google/android/exoplayer2/util/CodecSpecificDataUtil.java

@@ -90,7 +90,7 @@ public final class CodecSpecificDataUtil {
    */
   public static Pair<Integer, Integer> parseAacAudioSpecificConfig(byte[] audioSpecificConfig)
       throws ParserException {
-    return parseAacAudioSpecificConfig(new ParsableBitArray(audioSpecificConfig));
+    return parseAacAudioSpecificConfig(new ParsableBitArray(audioSpecificConfig), false);
   }
 
   /**
@@ -98,11 +98,13 @@ public final class CodecSpecificDataUtil {
    *
    * @param bitArray A {@link ParsableBitArray} containing the AudioSpecificConfig to parse. The
    *     position is advanced to the end of the AudioSpecificConfig.
+   * @param forceReadToEnd Whether the entire AudioSpecificConfig should be read. Required for
+   *     knowing the length of the configuration payload.
    * @return A pair consisting of the sample rate in Hz and the channel count.
    * @throws ParserException If the AudioSpecificConfig cannot be parsed as it's not supported.
    */
-  public static Pair<Integer, Integer> parseAacAudioSpecificConfig(ParsableBitArray bitArray)
-      throws ParserException {
+  public static Pair<Integer, Integer> parseAacAudioSpecificConfig(ParsableBitArray bitArray,
+      boolean forceReadToEnd) throws ParserException {
     int audioObjectType = getAacAudioObjectType(bitArray);
     int sampleRate = getAacSamplingFrequency(bitArray);
     int channelConfiguration = bitArray.readBits(4);
@@ -120,36 +122,38 @@ public final class CodecSpecificDataUtil {
       }
     }
 
-    switch (audioObjectType) {
-      case 1:
-      case 2:
-      case 3:
-      case 4:
-      case 6:
-      case 7:
-      case 17:
-      case 19:
-      case 20:
-      case 21:
-      case 22:
-      case 23:
-        parseGaSpecificConfig(bitArray, audioObjectType, channelConfiguration);
-        break;
-      default:
-        throw new ParserException("Unsupported audio object type: " + audioObjectType);
-    }
-    switch (audioObjectType) {
-      case 17:
-      case 19:
-      case 20:
-      case 21:
-      case 22:
-      case 23:
-        int epConfig = bitArray.readBits(2);
-        if (epConfig == 2 || epConfig == 3) {
-          throw new ParserException("Unsupported epConfig: " + epConfig);
-        }
-        break;
+    if (forceReadToEnd) {
+      switch (audioObjectType) {
+        case 1:
+        case 2:
+        case 3:
+        case 4:
+        case 6:
+        case 7:
+        case 17:
+        case 19:
+        case 20:
+        case 21:
+        case 22:
+        case 23:
+          parseGaSpecificConfig(bitArray, audioObjectType, channelConfiguration);
+          break;
+        default:
+          throw new ParserException("Unsupported audio object type: " + audioObjectType);
+      }
+      switch (audioObjectType) {
+        case 17:
+        case 19:
+        case 20:
+        case 21:
+        case 22:
+        case 23:
+          int epConfig = bitArray.readBits(2);
+          if (epConfig == 2 || epConfig == 3) {
+            throw new ParserException("Unsupported epConfig: " + epConfig);
+          }
+          break;
+      }
     }
     // For supported containers, bits_to_decode() is always 0.
     int channelCount = AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[channelConfiguration];