Add SupportsConfigChanges() to DemuxerStream.

media/filters/fake_demuxer_stream.cc

Index: media/filters/fake_demuxer_stream.cc
diff --git a/media/filters/fake_demuxer_stream.cc b/media/filters/fake_demuxer_stream.cc
index 51e4236b7df6d4ff3f884b27ffa92a1f28021861..5c5ca50ebd455563d809a0bdbc11029707ae6186 100644
--- a/media/filters/fake_demuxer_stream.cc
+++ b/media/filters/fake_demuxer_stream.cc
@@ -36,6 +36,7 @@ FakeDemuxerStream::FakeDemuxerStream(int num_configs,
     : task_runner_(base::MessageLoopProxy::current()),
       num_configs_left_(num_configs),
       num_buffers_in_one_config_(num_buffers_in_one_config),
+      config_changes_(num_configs > 1),
       is_encrypted_(is_encrypted),
       num_buffers_left_in_current_config_(num_buffers_in_one_config),
       num_buffers_returned_(0),
@@ -85,6 +86,10 @@ void FakeDemuxerStream::EnableBitstreamConverter() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 }
 
+bool FakeDemuxerStream::SupportsConfigChanges() {
+  return config_changes_;
+}
+
 void FakeDemuxerStream::HoldNextRead() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   read_to_hold_ = next_read_num_;