Add support for config changes during playback to FFmpegVideoDecoder.

media/mp4/mp4_stream_parser_unittest.cc

Index: media/mp4/mp4_stream_parser_unittest.cc
diff --git a/media/mp4/mp4_stream_parser_unittest.cc b/media/mp4/mp4_stream_parser_unittest.cc
index 830f35b968c640f55fd914ceab1f6601a79eb843..20c32f100cca69b86ad32efce102d7555e5b5c25 100644
--- a/media/mp4/mp4_stream_parser_unittest.cc
+++ b/media/mp4/mp4_stream_parser_unittest.cc
@@ -62,11 +62,6 @@ class MP4StreamParserTest : public testing::Test {
                    const VideoDecoderConfig& vc) {
     DVLOG(1) << "NewConfigF: audio=" << ac.IsValidConfig()
              << ", video=" << vc.IsValidConfig();
-
-    // TODO(strobe): Until http://crbug.com/122913 is fixed, we want to make
-    // sure that this callback isn't called more than once per stream. Remove
-    // when that bug is fixed.
-    EXPECT_FALSE(configs_received_);
     configs_received_ = true;
     return true;
   }