Add SupportsConfigChanges() to DemuxerStream.

media/filters/fake_demuxer_stream_unittest.cc

Index: media/filters/fake_demuxer_stream_unittest.cc
diff --git a/media/filters/fake_demuxer_stream_unittest.cc b/media/filters/fake_demuxer_stream_unittest.cc
index 553a2f080c38bbc90d71b31f2a16f520e34c6ebf..6ce8b39b10ae6036abac05c98e054afefb8c72dd 100644
--- a/media/filters/fake_demuxer_stream_unittest.cc
+++ b/media/filters/fake_demuxer_stream_unittest.cc
@@ -72,6 +72,7 @@ class FakeDemuxerStreamTest : public testing::Test {
         break;
 
       case CONFIG_CHANGED:
+        EXPECT_TRUE(stream_->SupportsConfigChanges());
         EXPECT_FALSE(read_pending_);
         EXPECT_EQ(DemuxerStream::kConfigChanged, status_);
         EXPECT_FALSE(buffer_.get());
@@ -244,4 +245,13 @@ TEST_F(FakeDemuxerStreamTest, Reset_BeforeEOS) {
   ReadAndExpect(EOS);
 }
 
+TEST_F(FakeDemuxerStreamTest, NoConfigChanges) {
+  stream_.reset(
+      new FakeDemuxerStream(1, kNumBuffersInOneConfig, false));
+  EXPECT_FALSE(stream_->SupportsConfigChanges());
+  for (int i = 0; i < kNumBuffersInOneConfig; ++i)
+    ReadAndExpect(OK);
+  ReadAndExpect(EOS);
+}
+
 }  // namespace media