To M56: Use ffmpeg for opus decoding, no need to maintain our decoder.

media/test/pipeline_integration_test.cc

Index: media/test/pipeline_integration_test.cc
diff --git a/media/test/pipeline_integration_test.cc b/media/test/pipeline_integration_test.cc
index d2493ed5cd9dc794e20338c3e2903b074eccb335..65b26e69f6a7c002d52e259f7e854f58ff52e422 100644
--- a/media/test/pipeline_integration_test.cc
+++ b/media/test/pipeline_integration_test.cc
@@ -1593,7 +1593,7 @@ TEST_F(PipelineIntegrationTest, MediaSource_ADTS_TimestampOffset) {
   EXPECT_EQ(592, pipeline_->GetBufferedTimeRanges().end(0).InMilliseconds());
 
   // Verify preroll is stripped.
-  EXPECT_HASH_EQ("-0.06,0.97,-0.90,-0.70,-0.53,-0.34,", GetAudioHash());
+  EXPECT_HASH_EQ("-0.25,0.67,0.04,0.14,-0.49,-0.41,", GetAudioHash());
 }
 
 TEST_F(PipelineIntegrationTest, BasicPlaybackHashed_MP3) {