Tighten up media::DecoderBuffer API contract for end of stream buffers.

media/filters/ffmpeg_demuxer_unittest.cc

Index: media/filters/ffmpeg_demuxer_unittest.cc
diff --git a/media/filters/ffmpeg_demuxer_unittest.cc b/media/filters/ffmpeg_demuxer_unittest.cc
index d1c2c04ac8b97e4da24a2a43205a0709ac5b2c38..72b64ae688905e757a2d800b6794b29965f14247 100644
--- a/media/filters/ffmpeg_demuxer_unittest.cc
+++ b/media/filters/ffmpeg_demuxer_unittest.cc
@@ -45,8 +45,6 @@ static void EosOnReadDone(bool* got_eos_buffer,
   EXPECT_EQ(status, DemuxerStream::kOk);
   if (buffer->IsEndOfStream()) {
     *got_eos_buffer = true;
-    EXPECT_TRUE(!buffer->GetData());
-    EXPECT_EQ(buffer->GetDataSize(), 0);
     return;
   }