Return 0 instead of AVERROR_EOF for reads at or past the end of a file.

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 5ba6fd324101b37d8be69c4fb404138d84058ecb..aec72ea39eadfbfbeaee7ccb4e6df80433f3f1f3 100644
--- a/media/filters/ffmpeg_demuxer_unittest.cc
+++ b/media/filters/ffmpeg_demuxer_unittest.cc
@@ -682,8 +682,8 @@ TEST_F(FFmpegDemuxerTest, ProtocolRead) {
   EXPECT_TRUE(demuxer->GetPosition(&position));
   EXPECT_EQ(1024, position);
 
-  // Third read will get an end-of-file error.
-  EXPECT_EQ(AVERROR_EOF, demuxer->Read(512, kBuffer));
+  // Third read will get an end-of-file error, which is represented as zero.
+  EXPECT_EQ(0, demuxer->Read(512, kBuffer));
 
   // This read complete signal is generated when demuxer is stopped.
   EXPECT_CALL(*demuxer, SignalReadCompleted(DataSource::kReadError));