Bug 1928798 - do not return fatal error if the initialization failed,…

… try again with another state machine. r=jrmuizel, a=RyanVM

It's possible that the initialization failure is caused by the user's
device not supporting the media engine pipeline. In this case, we
should attempt to use another state machine for playback instead of
simply returning an error.

Differential Revision: https://phabricator.services.mozilla.com/D227773

dom/media/ExternalEngineStateMachine.cpp

@@ -259,9 +259,12 @@ void ExternalEngineStateMachine::OnEngineInitFailure() {
   auto* state = mState.AsInitEngine();
   state->mEngineInitRequest.Complete();
   state->mInitPromise = nullptr;
-  // TODO : Should fallback to the normal playback with media engine.
-  ReportTelemetry(NS_ERROR_DOM_MEDIA_FATAL_ERR);
-  DecodeError(MediaResult(NS_ERROR_DOM_MEDIA_FATAL_ERR, __func__));
+  // Even if we failed to initialize the media engine, we still want to try
+  // again with the normal state machine, so don't return a fatal error, return
+  // NS_ERROR_DOM_MEDIA_EXTERNAL_ENGINE_NOT_SUPPORTED_ERR instead.
+  ReportTelemetry(NS_ERROR_DOM_MEDIA_MEDIA_ENGINE_INITIALIZATION_ERR);
+  DecodeError(MediaResult(NS_ERROR_DOM_MEDIA_EXTERNAL_ENGINE_NOT_SUPPORTED_ERR,
+                          __func__));
 }
 
 void ExternalEngineStateMachine::ReadMetadata() {

xpcom/base/ErrorList.py

@@ -1191,6 +1191,7 @@ def SUCCESS(code):
     errors["NS_ERROR_DOM_MEDIA_DENIED_IN_NON_UTILITY"] = FAILURE(104)
     errors["NS_ERROR_DOM_MEDIA_RANGE_ERR"] = FAILURE(105)
     errors["NS_ERROR_DOM_MEDIA_TYPE_ERR"] = FAILURE(106)
+    errors["NS_ERROR_DOM_MEDIA_MEDIA_ENGINE_INITIALIZATION_ERR"] = FAILURE(107)
 
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 # 42: NS_ERROR_MODULE_URL_CLASSIFIER