Bug 1741775 - Remove LayersBackend::LAYERS_OPENGL r=gfx-reviewers,nical

LayersBackend::LAYERS_OPENGL is not used any more.

Code under widget/uikit is dead code.

Differential Revision: https://phabricator.services.mozilla.com/D131461

gfx/layers/CanvasRenderer.cpp

@@ -93,7 +93,6 @@ TextureType TexTypeForWebgl(KnowsCompositor* const knowsCompositor) {
     case LayersBackend::LAYERS_NONE:
       return TextureType::Unknown;
 
-    case LayersBackend::LAYERS_OPENGL:
     case LayersBackend::LAYERS_WR:
       break;
   }

gfx/layers/LayersTypes.cpp

@@ -30,8 +30,6 @@ const char* GetLayersBackendName(LayersBackend aBackend) {
   switch (aBackend) {
     case LayersBackend::LAYERS_NONE:
       return "none";
-    case LayersBackend::LAYERS_OPENGL:
-      return "opengl";
     case LayersBackend::LAYERS_WR:
       MOZ_ASSERT(gfx::gfxVars::UseWebRender());
       if (gfx::gfxVars::UseSoftwareWebRender()) {

gfx/layers/LayersTypes.h

@@ -165,12 +165,7 @@ typedef BaseTransactionId<CompositionOpportunityType> CompositionOpportunityId;
 /// content in the window.
 enum class WindowKind : int8_t { MAIN = 0, SECONDARY, LAST };
 
-enum class LayersBackend : int8_t {
-  LAYERS_NONE = 0,
-  LAYERS_OPENGL,
-  LAYERS_WR,
-  LAYERS_LAST
-};
+enum class LayersBackend : int8_t { LAYERS_NONE = 0, LAYERS_WR, LAYERS_LAST };
 
 enum class WebRenderBackend : int8_t { HARDWARE = 0, SOFTWARE, LAST };
 

gfx/layers/client/TextureClient.cpp

@@ -275,9 +275,8 @@ static TextureType GetTextureType(gfx::SurfaceFormat aFormat,
 #endif
 
 #ifdef MOZ_WAYLAND
-  if ((layersBackend == LayersBackend::LAYERS_OPENGL ||
-       (layersBackend == LayersBackend::LAYERS_WR &&
-        !aKnowsCompositor->UsingSoftwareWebRender())) &&
+  if ((layersBackend == LayersBackend::LAYERS_WR &&
+       !aKnowsCompositor->UsingSoftwareWebRender()) &&
       widget::GetDMABufDevice()->IsDMABufTexturesEnabled() &&
       aFormat != SurfaceFormat::A8) {
     return TextureType::DMABUF;

widget/uikit/nsWindow.mm

@@ -239,8 +239,7 @@ class nsAutoRetainUIKitObject {
 - (BOOL)isUsingMainThreadOpenGL {
   if (!mGeckoChild || ![self window]) return NO;
 
-  return mGeckoChild->GetLayerManager(nullptr)->GetBackendType() ==
-         mozilla::layers::LayersBackend::LAYERS_OPENGL;
+  return NO;
 }
 
 - (void)drawUsingOpenGL {