Update WebMClusterParser to compute durations for all StreamParserBuffers.

media/webm/webm_cluster_parser_unittest.cc

Index: media/webm/webm_cluster_parser_unittest.cc
diff --git a/media/webm/webm_cluster_parser_unittest.cc b/media/webm/webm_cluster_parser_unittest.cc
index d553c1da81db6e19178c6d0db0a4c164832d6992..cbf3150b50e180cb3b66663f8ca9d1008fdcb79e 100644
--- a/media/webm/webm_cluster_parser_unittest.cc
+++ b/media/webm/webm_cluster_parser_unittest.cc
@@ -38,11 +38,11 @@ struct BlockInfo {
 };
 
 const BlockInfo kDefaultBlockInfo[] = {
-  { kAudioTrackNum, 0, -1, true },
-  { kAudioTrackNum, 23, -1, true },
+  { kAudioTrackNum, 0, 23, true },
+  { kAudioTrackNum, 23, 23, true },
   { kVideoTrackNum, kVideoDefaultDurationInMs, kVideoDefaultDurationInMs,
     true },
-  { kAudioTrackNum, 46, -1, true },
+  { kAudioTrackNum, 46, 23, false },
   { kVideoTrackNum, 2 * kVideoDefaultDurationInMs, kVideoDefaultDurationInMs,
     true },
 };
@@ -242,7 +242,7 @@ TEST_F(WebMClusterParserTest, ParseBlockGroup) {
 
 TEST_F(WebMClusterParserTest, ParseSimpleBlockAndBlockGroupMixture) {
   const BlockInfo kBlockInfo[] = {
-    { kAudioTrackNum, 0, -1, true },
+    { kAudioTrackNum, 0, 23, true },
     { kAudioTrackNum, 23, 23, false },
     { kVideoTrackNum, kVideoDefaultDurationInMs, kVideoDefaultDurationInMs,
       true },