Add SupportsConfigChanges() to DemuxerStream.

media/filters/decrypting_demuxer_stream.cc

Index: media/filters/decrypting_demuxer_stream.cc
diff --git a/media/filters/decrypting_demuxer_stream.cc b/media/filters/decrypting_demuxer_stream.cc
index b069567a0645966539c59511a34a28401c32294c..9bc4e01255e9dfb14fea636aba45808d6dad681d 100644
--- a/media/filters/decrypting_demuxer_stream.cc
+++ b/media/filters/decrypting_demuxer_stream.cc
@@ -161,6 +161,11 @@ void DecryptingDemuxerStream::EnableBitstreamConverter() {
   demuxer_stream_->EnableBitstreamConverter();
 }
 
+bool DecryptingDemuxerStream::SupportsConfigChanges() {
+  DCHECK(demuxer_stream_);

[scherkus (not reviewing), 2014/03/25 23:17:58]

we tend to avoid these DCHECK()s as null pointer dereferences have their own
built-in DCHECK-like behaviour that even works in release mode (i.e., they
crash)

(also our code would be littered with 1000s of DCHECK()s for valid pointers! the
only time we tend to use them is if the pointer isn't immediately dereferenced
[e.g., pass a pointer into a ctor that requires it to be non-null, but you only
use the pointer sometime way after the ctor completes])

+  return demuxer_stream_->SupportsConfigChanges();
+}
+
 DecryptingDemuxerStream::~DecryptingDemuxerStream() {
   DVLOG(2) << __FUNCTION__ << " : state_ = " << state_;
 }