Implement MP3 ConstantBitrateSeeker.getDataEndPosition()

This is needed to correctly handle files with trailing non-MP3 data
(which is indicated by the length in the `Info` frame being shorter than
the overall length of the file).

The test file was generated by appending 150kB of `DEADBEEF` onto the
end of `test-cbr-info-header.mp3`, and the test asserts that the
extracted samples are identical.

Issue: androidx/media#1480

PiperOrigin-RevId: 658727595
(cherry picked from commit b09cea9e3a)

RELEASENOTES.md

@@ -7,6 +7,9 @@
 *   Transformer:
 *   Track Selection:
 *   Extractors:
+    *   MP3: Fix `Searched too many bytes` error by correctly ignoring trailing
+        non-MP3 data based on the length field in an `Info` frame
+        ([#1480](https://github.com/androidx/media/issues/1480)).
 *   Audio:
 *   Video:
 *   Text:

libraries/extractor/src/main/java/androidx/media3/extractor/mp3/ConstantBitrateSeeker.java

@@ -25,6 +25,7 @@ import androidx.media3.extractor.MpegAudioUtil;
 /* package */ final class ConstantBitrateSeeker extends ConstantBitrateSeekMap implements Seeker {
 
   private final int bitrate;
+  private final long dataEndPosition;
 
   /**
    * Constructs an instance.
@@ -60,6 +61,7 @@ import androidx.media3.extractor.MpegAudioUtil;
       boolean allowSeeksIfLengthUnknown) {
     super(inputLength, firstFramePosition, bitrate, frameSize, allowSeeksIfLengthUnknown);
     this.bitrate = bitrate;
+    dataEndPosition = inputLength != C.LENGTH_UNSET ? inputLength : C.INDEX_UNSET;
   }
 
   @Override
@@ -69,7 +71,7 @@ import androidx.media3.extractor.MpegAudioUtil;
 
   @Override
   public long getDataEndPosition() {
-    return C.INDEX_UNSET;
+    return dataEndPosition;
   }
 
   @Override

libraries/extractor/src/test/java/androidx/media3/extractor/mp3/Mp3ExtractorTest.java

@@ -54,6 +54,21 @@ public final class Mp3ExtractorTest {
         Mp3Extractor::new, "media/mp3/test-cbr-info-header-pcut-frame.mp3", simulationConfig);
   }
 
+  // https://github.com/androidx/media/issues/1480
+  @Test
+  public void mp3SampleWithInfoHeaderAndTrailingGarbage() throws Exception {
+    // This test file is test-cbr-info-header.mp3 with 150kB of 0xDEADBEEF garbage appended on the
+    // end. The test asserts that the extracted samples are the same as for
+    // test-cbr-info-header.mp3.
+    ExtractorAsserts.assertBehavior(
+        Mp3Extractor::new,
+        "media/mp3/test-cbr-info-header-trailing-garbage.mp3",
+        new AssertionConfig.Builder()
+            .setDumpFilesPrefix("extractordumps/mp3/test-cbr-info-header.mp3")
+            .build(),
+        simulationConfig);
+  }
+
   @Test
   public void mp3SampleWithCbrSeeker() throws Exception {
     ExtractorAsserts.assertBehavior(