Bug 1548686 - only add RemoteDecoderModule in CreatePDMs if e10s. r=jya

This can cause 1proc tests to fail because no decoder ends up supporting
a format.  The particular case was enabling Vorbis decoding on RDD.

Differential Revision: https://phabricator.services.mozilla.com/D29766

--HG--
extra : moz-landing-system : lando

dom/media/platforms/PDMFactory.cpp

@@ -16,6 +16,7 @@
 #include "MediaInfo.h"
 #include "VPXDecoder.h"
 #include "gfxPrefs.h"
+#include "nsIXULRuntime.h" // for BrowserTabsRemoteAutostart
 #include "mozilla/CDMProxy.h"
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/GpuDecoderModule.h"
@@ -344,7 +345,8 @@ void PDMFactory::CreatePDMs() {
     return;
   }
 
-  if (StaticPrefs::MediaRddProcessEnabled()) {
+  if (StaticPrefs::MediaRddProcessEnabled()
+      && BrowserTabsRemoteAutostart()) {
     m = new RemoteDecoderModule;
     StartupPDM(m);
   }

dom/media/platforms/agnostic/AgnosticDecoderModule.cpp

@@ -26,7 +26,8 @@ bool AgnosticDecoderModule::SupportsMimeType(
       VPXDecoder::IsVPX(aMimeType) || OpusDataDecoder::IsOpus(aMimeType) ||
       WaveDataDecoder::IsWave(aMimeType) || TheoraDecoder::IsTheora(aMimeType);
   if (!StaticPrefs::MediaRddVorbisEnabled() ||
-      !StaticPrefs::MediaRddProcessEnabled()) {
+      !StaticPrefs::MediaRddProcessEnabled() ||
+      !BrowserTabsRemoteAutostart()) {
     supports |= VorbisDataDecoder::IsVorbis(aMimeType);
   }
 #ifdef MOZ_AV1