Fix some documentation nits.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148776593

extensions/gvr/src/main/java/com/google/android/exoplayer2/ext/gvr/GvrAudioProcessor.java

@@ -43,6 +43,9 @@ public final class GvrAudioProcessor implements AudioProcessor {
   private float y;
   private float z;
 
+  /**
+   * Creates a new GVR audio processor.
+   */
   public GvrAudioProcessor() {
     // Use the identity for the initial orientation.
     w = 1f;

library/src/main/java/com/google/android/exoplayer2/C.java

@@ -484,7 +484,7 @@ public final class C {
    * {@link ExoPlayer#sendMessages} or {@link ExoPlayer#blockingSendMessages}. The message object
    * should be a {@link android.media.PlaybackParams}, or null, which will be used to configure the
    * underlying {@link android.media.AudioTrack}. The message object should not be modified by the
-   * caller after it has been passed
+   * caller after it has been passed.
    */
   public static final int MSG_SET_PLAYBACK_PARAMS = 3;
 

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

@@ -33,7 +33,7 @@ import java.util.List;
 public final class DefaultTsPayloadReaderFactory implements TsPayloadReader.Factory {
 
   /**
-   * Flags controlling elementary stream readers behaviour.
+   * Flags controlling elementary stream readers' behavior.
    */
   @Retention(RetentionPolicy.SOURCE)
   @IntDef(flag = true, value = {FLAG_ALLOW_NON_IDR_KEYFRAMES, FLAG_IGNORE_AAC_STREAM,