Add more DecoderSelector traces to debug issue.

Adds a STEP trace with the decoder name being initialized as well
as a STEP trace when DecryptingDemuxerStream is initialized.

BUG=883620
TEST=none

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I958b4f98836e8e4d43ec59931d3cd952c52a09e1
Reviewed-on: https://chromium-review.googlesource.com/c/1263576
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Dan Sanders <sandersd@chromium.org>
Reviewed-by: Dan Sanders <sandersd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596973}

media/filters/decoder_selector.cc

@@ -25,6 +25,8 @@
 
 namespace media {
 
+const char kSelectDecoderTrace[] = "DecoderSelector::SelectDecoder";
+
 template <DemuxerStream::Type StreamType>
 DecoderSelector<StreamType>::DecoderSelector(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
@@ -67,13 +69,14 @@ void DecoderSelector<StreamType>::SelectDecoder(
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(select_decoder_cb);
   DCHECK(!select_decoder_cb_);
-  TRACE_EVENT_ASYNC_BEGIN1("media", "DecoderSelector::SelectDecoder", this,
-                           "type", DemuxerStream::GetTypeName(StreamType));
-
   select_decoder_cb_ = std::move(select_decoder_cb);
   output_cb_ = std::move(output_cb);
   config_ = traits_->GetDecoderConfig(stream_);
 
+  TRACE_EVENT_ASYNC_BEGIN2("media", kSelectDecoderTrace, this, "type",
+                           DemuxerStream::GetTypeName(StreamType), "config",
+                           config_.AsHumanReadableString());
+
   if (!config_.IsValidConfig()) {
     DLOG(ERROR) << "Invalid stream config";
     ReturnNullDecoder();
@@ -145,6 +148,8 @@ void DecoderSelector<StreamType>::InitializeDecoder() {
   decoder_ = std::move(decoders_.front());
   decoders_.erase(decoders_.begin());
   is_platform_decoder_ = decoder_->IsPlatformDecoder();
+  TRACE_EVENT_ASYNC_STEP_INTO0("media", kSelectDecoderTrace, this,
+                               decoder_->GetDisplayName());
 
   DVLOG(2) << __func__ << ": initializing " << decoder_->GetDisplayName();
   const bool is_live = stream_->liveness() == DemuxerStream::LIVENESS_LIVE;
@@ -187,6 +192,8 @@ void DecoderSelector<StreamType>::InitializeDecryptingDemuxerStream() {
   DCHECK(decoders_.empty());
   DCHECK(config_.is_encrypted());
   DCHECK(cdm_context_);
+  TRACE_EVENT_ASYNC_STEP_INTO0("media", kSelectDecoderTrace, this,
+                               "DecryptingDemuxerStream");
 
   decrypting_demuxer_stream_ = std::make_unique<DecryptingDemuxerStream>(
       task_runner_, media_log_, waiting_for_decryption_key_cb_);
@@ -229,7 +236,7 @@ template <DemuxerStream::Type StreamType>
 void DecoderSelector<StreamType>::RunSelectDecoderCB() {
   DCHECK(select_decoder_cb_);
   TRACE_EVENT_ASYNC_END2(
-      "media", "DecoderSelector::SelectDecoder", this, "type",
+      "media", kSelectDecoderTrace, this, "type",
       DemuxerStream::GetTypeName(StreamType), "decoder",
       base::StringPrintf(
           "%s (%s)", decoder_ ? decoder_->GetDisplayName().c_str() : "null",