Adds NotifyError for Status types

And, as a use case, logs failure reason for decoders when they
can't be initialized.

This currently just dumps the status as JSON into the media log. I've
not implemented a frontend for this in devtools yet.

Change-Id: I3aea5f027078e3f2979eaeeebc08549aa8a393a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2141622Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Ted Meyer <tmathmeyer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757508}

media/base/media_log.cc

@@ -65,6 +65,13 @@ void MediaLog::NotifyError(PipelineStatus status) {
   AddLogRecord(std::move(record));
 }
 
+void MediaLog::NotifyError(Status status) {
+  DCHECK(!status.is_ok());
+  std::string output_str;
+  base::JSONWriter::Write(MediaSerialize(status), &output_str);
+  AddMessage(MediaLogMessageLevel::kERROR, output_str);
+}
+
 void MediaLog::OnWebMediaPlayerDestroyedLocked() {}
 void MediaLog::OnWebMediaPlayerDestroyed() {
   AddEvent<MediaLogEvent::kWebMediaPlayerDestroyed>();

media/base/media_log.h

@@ -81,6 +81,9 @@ class MEDIA_EXPORT MediaLog {
   // TODO(tmathmeyer) replace with Status when that's ready.
   void NotifyError(PipelineStatus status);
 
+  // Notify a non-ok Status. This method Should _not_ be given an OK status.
+  void NotifyError(Status status);
+
   // Notify the media log that the player is destroyed. Some implementations
   // will want to change event handling based on this.
   void OnWebMediaPlayerDestroyed();

media/filters/decoder_selector.cc

@@ -165,6 +165,14 @@ void DecoderSelector<StreamType>::OnDecoderInitializeDone(Status status) {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   if (!status.is_ok()) {
+    // TODO(tmathmeyer) this might be noisy in media log. Consider batching
+    // all failures as causes to a single Status object and only surfacing it if
+    // decoder selection fails entirely.
+    media_log_->NotifyError(
+        Status(StatusCode::kDecoderFailedInitialization)
+            .WithData("Decoder name", decoder_->GetDisplayName())
+            .AddCause(std::move(status)));
+
     // Try the next decoder on the list.
     decoder_.reset();
     InitializeDecoder();