Use passthrough decoder for (E)AC3 formats

media/BUILD.gn

Index: media/BUILD.gn
diff --git a/media/BUILD.gn b/media/BUILD.gn
index 8d97ec513ba2e43f871c4a10b1db5d90b40fb9c7..d5cf4f5f4ad0fff92ecf584087f30b5b45148183 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -201,6 +201,8 @@ component("media") {
     "filters/webvtt_util.h",
     "filters/wsola_internals.cc",
     "filters/wsola_internals.h",
+    "formats/ac3/ac3_util.cc",
+    "formats/ac3/ac3_util.h",
     "formats/common/offset_byte_queue.cc",
     "formats/common/offset_byte_queue.h",
     "formats/webm/webm_audio_client.cc",
@@ -377,10 +379,10 @@ component("media") {
   }
 
   if (disable_ffmpeg_video_decoders) {
-      sources -= [
-        "filters/decrypting_video_decoder.cc",
-        "filters/decrypting_video_decoder.h",
-      ]
+    sources -= [
+      "filters/decrypting_video_decoder.cc",
+      "filters/decrypting_video_decoder.h",
+    ]
   }
 
   if (is_android) {
@@ -659,9 +661,7 @@ source_set("unit_tests") {
     ]
 
     if (!disable_ffmpeg_video_decoders) {
-      sources += [
-        "filters/ffmpeg_video_decoder_unittest.cc",
-      ]
+      sources += [ "filters/ffmpeg_video_decoder_unittest.cc" ]
     }
   }