Simplify AudioSplicer logic which slots buffers before or after a splice point.

media/filters/decoder_stream.h

Index: media/filters/decoder_stream.h
diff --git a/media/filters/decoder_stream.h b/media/filters/decoder_stream.h
index 2fd2a552d2706395f748630aa4746a324dcfbd0d..4992141443b3410d71c050318fb2b160807a870b 100644
--- a/media/filters/decoder_stream.h
+++ b/media/filters/decoder_stream.h
@@ -89,6 +89,9 @@ class MEDIA_EXPORT DecoderStream {
 
   // Allows callers to register for notification of splice buffers from the
   // demuxer.  I.e., DecoderBuffer::splice_timestamp() is not kNoTimestamp().
+  //
+  // The observer will be notified of all buffers with a splice_timestamp() and
+  // the first buffer after which has a splice_timestamp() of kNoTimestamp().

[wolenetz, 2014/04/17 18:24:03]

Clarification of my understanding: Is the intent here that SpliceObserverCB
(AudioRendererImpl::OnNewSpliceBuffer currently) is notified of each in sequence
of the splice timestamps for all pre-splice buffers followed by the
post-splice-buffer? Is the order of splice notification vs read_cb_ undocumented
here? (If so, nit: please add that documentation. My understanding is there
could be some decoder delay, but read_cb_ should be executed for the decoded
active splice buffer at some point in time *after* the associated
spliceobservercb was called. Is this correct? Could there be more than one
buffer's decoded contents passed to read_cb_ in the interim, and would the
renderer_impl take such into account?)

[DaleCurtis, 2014/04/17 20:03:18]

I'll fix the comment in StreamParserBuffer() to document this better.  The
documentation here is a statement of what will happen, not how splices are made.

Since the first post splice buffer happens after a config change, we don't need
to worry about any additional buffers in the queue when marking the end of pre
splice buffers.

   typedef base::Callback<void(base::TimeDelta)> SpliceObserverCB;
   void set_splice_observer(const SpliceObserverCB& splice_observer) {
     splice_observer_cb_ = splice_observer;
@@ -180,6 +183,10 @@ class MEDIA_EXPORT DecoderStream {
   SpliceObserverCB splice_observer_cb_;
   ConfigChangeObserverCB config_change_observer_cb_;
 
+  // If a splice_timestamp() has been seen, this is true until a
+  // splice_timestamp() of kNoTimestamp() is encountered.
+  bool active_splice_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<DecoderStream<StreamType> > weak_factory_;