Bug 1884719 - part3 : add a by-pass pref for testing. r=media-playback-reviewers,ci-and-tooling,jmaher,padenot

Ideally, we should run `wmfme` on the gpu worker in order to access
video hardware decoding. However, when switching task to the gpu
worker, there are some tests starting failed on the try server [1].

Therefore, adding this pref temporarily to bypass the gfx check until
we figure out why those tests fail on the gpu worker.

[1] https://treeherder.mozilla.org/jobs?repo=try&revision=bd9a68c7c259ba9028051c8898ddd69384616ac5&selectedTaskRun=OvNqUv77Q5OVeBDlIhWQ5g.0

Differential Revision: https://phabricator.services.mozilla.com/D204443

dom/media/platforms/wmf/MFMediaEngineDecoderModule.cpp

@@ -101,7 +101,8 @@ media::DecodeSupportSet MFMediaEngineDecoderModule::SupportInternal(
     return media::DecodeSupportSet{};
   }
   // Only support hardware decoding.
-  if (!gfx::gfxVars::CanUseHardwareVideoDecoding()) {
+  if (!gfx::gfxVars::CanUseHardwareVideoDecoding() &&
+      !StaticPrefs::media_wmf_media_engine_bypass_gfx_blocklist()) {
     return media::DecodeSupportSet{};
   }
   bool supports = false;

modules/libpref/init/StaticPrefList.yaml

@@ -10289,6 +10289,12 @@
     value: 2
     mirror: always
 
+# Bypass the gfx block list check for the media engine playback.
+-   name: media.wmf.media-engine.bypass-gfx-blocklist
+    type: RelaxedAtomicBool
+    value: false
+    mirror: always
+
 # [TEST-ONLY] Use Media Foundation Clearkey CDM for EME related testing.
 -   name: media.eme.wmf.clearkey.enabled
     type: RelaxedAtomicBool

taskcluster/ci/test/variants.yml

@@ -355,6 +355,7 @@ wmf-media-engine:
                 - "--setpref=media.wmf.media-engine.enabled=1"
                 - "--setpref=media.wmf.media-engine.channel-decoder.enabled=true"
                 - "--setpref=media.eme.wmf.clearkey.enabled=true"
+                - "--setpref=media.wmf.media-engine.bypass-gfx-blocklist=true"
 
 media-gpu:
     description: "{description} for running media tests on the GPU worker"