Add support for incremental cluster parsing.

media/webm/webm_cluster_parser.cc

Index: media/webm/webm_cluster_parser.cc
diff --git a/media/webm/webm_cluster_parser.cc b/media/webm/webm_cluster_parser.cc
index 8eb045cbf8a3e3ffdf577868bce4c0dd3eb86683..995578cd988012600de699b6c4651fd5eb7cc57f 100644
--- a/media/webm/webm_cluster_parser.cc
+++ b/media/webm/webm_cluster_parser.cc
@@ -33,11 +33,31 @@ WebMClusterParser::WebMClusterParser(int64 timecode_scale,
 WebMClusterParser::~WebMClusterParser() {}
 
 int WebMClusterParser::Parse(const uint8* buf, int size) {

[scherkus (not reviewing), 2011/12/03 01:56:51]

perhaps the .h docs need to be updated because I'm not quite clear on what this
function is supposed to be doing

-  last_block_timecode_ = -1;
-  cluster_timecode_ = -1;
   audio_buffers_.clear();
   video_buffers_.clear();
 
+  int id;
+  int64 element_size;
+  int result = WebMParseElementHeader(buf, size, &id, &element_size);
+
+  if (result <= 0)
+    return result;
+
+  if (id == kWebMIdCues) {

[scherkus (not reviewing), 2011/12/03 01:56:51]

sanity check: this branch checks for a CUES section then skips it?

+    if (size < (result + element_size)) {
+      // We don't have the whole element yet. Signal we need more data.
+      return 0;
+    }
+    // Skip the element.
+    return result + element_size;
+  } else if (id != kWebMIdCluster) {

[scherkus (not reviewing), 2011/12/03 01:56:51]

nit: no need for else

+    VLOG(1) << "Unexpected ID 0x" << std::hex << id;

[scherkus (not reviewing), 2011/12/03 01:56:51]

DVLOG

+    return -1;
+  }
+
+  last_block_timecode_ = -1;
+  cluster_timecode_ = -1;
+
   return WebMParseListElement(buf, size, kWebMIdCluster, 1, this);
 }