Enable pcm_s32le audio decoding.

media/base/sample_format.cc

Index: media/base/sample_format.cc
diff --git a/media/base/sample_format.cc b/media/base/sample_format.cc
index 464fc1b6f578e0f4187f40365d18f4ef8922a20b..0c84f55df68ec6f416257ea44379f36a046dfa25 100644
--- a/media/base/sample_format.cc
+++ b/media/base/sample_format.cc
@@ -17,6 +17,7 @@ int SampleFormatToBytesPerChannel(SampleFormat sample_format) {
     case kSampleFormatS16:
     case kSampleFormatPlanarS16:
       return 2;
+    case kSampleFormatS24:
     case kSampleFormatS32:
     case kSampleFormatF32:
     case kSampleFormatPlanarF32:
@@ -36,6 +37,8 @@ const char* SampleFormatToString(SampleFormat sample_format) {
       return "Unsigned 8-bit with bias of 128";
     case kSampleFormatS16:
       return "Signed 16-bit";
+    case kSampleFormatS24:
+      return "Signed 24-bit";
     case kSampleFormatS32:
       return "Signed 32-bit";
     case kSampleFormatF32: