Bug 1733094 - Assume UseWebRender for FindVisual, r=stransky,emilio

`gfxVars::UseWebRender()` now always returns `true` thus stop passing
it around as argument.

At the same time, WR does not require a depth buffer any more, thus
stop requesting it when choosing a matching XVisual.

While on it, also stop requesting an alpha channel were it shouldn't
be needed. This point will require some regression testing, making
this patch 95 material.

Differential Revision: https://phabricator.services.mozilla.com/D126922

gfx/gl/GLContextEGL.h

@@ -113,8 +113,7 @@ class GLContextEGL final : public GLContext {
       widget::CompositorWidget* aCompositorWidget, const EGLConfig aConfig);
 
 #ifdef MOZ_X11
-  static bool FindVisual(bool aUseWebRender, bool useAlpha,
-                         int* const out_visualId);
+  static bool FindVisual(bool useAlpha, int* const out_visualId);
 #endif
 
  protected:

gfx/gl/GLContextGLX.h

@@ -24,8 +24,8 @@ class GLContextGLX : public GLContext {
       GLXDrawable drawable, GLXFBConfig cfg, bool deleteDrawable,
       gfxXlibSurface* pixmap);
 
-  static bool FindVisual(Display* display, int screen, bool useWebRender,
-                         bool useAlpha, int* const out_visualId);
+  static bool FindVisual(Display* display, int screen, bool useAlpha,
+                         int* const out_visualId);
 
   // Finds a GLXFBConfig compatible with the provided window.
   static bool FindFBConfigForWindow(

gfx/gl/GLContextProviderEGL.cpp

@@ -1110,8 +1110,7 @@ static EGLConfig ChooseConfig(EglDisplay& egl, const GLContextCreateDesc& desc,
 
 #ifdef MOZ_X11
 /* static */
-bool GLContextEGL::FindVisual(bool aUseWebRender, bool useAlpha,
-                              int* const out_visualId) {
+bool GLContextEGL::FindVisual(bool useAlpha, int* const out_visualId) {
   nsCString discardFailureId;
   const auto egl = DefaultEglDisplay(&discardFailureId);
   if (!egl) {
@@ -1122,7 +1121,8 @@ bool GLContextEGL::FindVisual(bool aUseWebRender, bool useAlpha,
 
   EGLConfig config;
   const int bpp = useAlpha ? 32 : 24;
-  if (!CreateConfig(*egl, &config, bpp, aUseWebRender, /* aUseGles */ false)) {
+  if (!CreateConfig(*egl, &config, bpp, /* aEnableDepthBuffer */ false,
+                    /* aUseGles */ false)) {
     gfxCriticalNote
         << "GLContextEGL::FindVisual(): Failed to create EGLConfig!";
     return false;

gfx/gl/GLContextProviderGLX.cpp

@@ -700,8 +700,8 @@ static bool ChooseConfig(GLXLibrary* glx, Display* display, int screen,
   return false;
 }
 
-bool GLContextGLX::FindVisual(Display* display, int screen, bool useWebRender,
-                              bool useAlpha, int* const out_visualId) {
+bool GLContextGLX::FindVisual(Display* display, int screen, bool useAlpha,
+                              int* const out_visualId) {
   if (!sGLXLibrary.EnsureInitialized(display)) {
     return false;
   }
@@ -738,7 +738,6 @@ bool GLContextGLX::FindVisual(Display* display, int screen, bool useWebRender,
 
   const int bpp = useAlpha ? 32 : 24;
   const int alphaSize = useAlpha ? 8 : 0;
-  const int depthSize = useWebRender ? 24 : 0;
 
   for (auto& cur : visualInfos) {
     const auto fnConfigMatches = [&](const int pname, const int expected) {
@@ -761,7 +760,7 @@ bool GLContextGLX::FindVisual(Display* display, int screen, bool useWebRender,
         fnConfigMatches(LOCAL_GLX_GREEN_SIZE, 8) &&
         fnConfigMatches(LOCAL_GLX_BLUE_SIZE, 8) &&
         fnConfigMatches(LOCAL_GLX_ALPHA_SIZE, alphaSize) &&
-        fnConfigMatches(LOCAL_GLX_DEPTH_SIZE, depthSize)) {
+        fnConfigMatches(LOCAL_GLX_DEPTH_SIZE, 0)) {
       *out_visualId = cur.visualid;
       return true;
     }

widget/gtk/nsWindow.cpp

@@ -5143,17 +5143,12 @@ static GdkWindow* CreateGdkWindow(GdkWindow* parent, GtkWidget* widget) {
   return window;
 }
 
-// Configure GL visual on X11. We add alpha silently
-// if we use WebRender to workaround NVIDIA specific Bug 1663273.
+// Configure GL visual on X11.
 bool nsWindow::ConfigureX11GLVisual(bool aUseAlpha) {
   if (!GdkIsX11Display()) {
     return false;
   }
 
-  // If using WebRender on X11, we need to select a visual with a depth
-  // buffer, as well as an alpha channel if transparency is requested. This
-  // must be done before the widget is realized.
-  bool useWebRender = gfx::gfxVars::UseWebRender();
   auto* screen = gtk_widget_get_screen(mShell);
   int visualId = 0;
   bool haveVisual;
@@ -5170,11 +5165,10 @@ bool nsWindow::ConfigureX11GLVisual(bool aUseAlpha) {
   if (!gfxVars::UseEGL() || isMesa) {
     auto* display = GDK_DISPLAY_XDISPLAY(gtk_widget_get_display(mShell));
     int screenNumber = GDK_SCREEN_XNUMBER(screen);
-    haveVisual = GLContextGLX::FindVisual(display, screenNumber, useWebRender,
-                                          aUseAlpha || useWebRender, &visualId);
+    haveVisual =
+        GLContextGLX::FindVisual(display, screenNumber, aUseAlpha, &visualId);
   } else {
-    haveVisual = GLContextEGL::FindVisual(useWebRender,
-                                          aUseAlpha || useWebRender, &visualId);
+    haveVisual = GLContextEGL::FindVisual(aUseAlpha, &visualId);
   }
 
   GdkVisual* gdkVisual = nullptr;
@@ -5185,7 +5179,7 @@ bool nsWindow::ConfigureX11GLVisual(bool aUseAlpha) {
   }
   if (!gdkVisual) {
     NS_WARNING("We're missing X11 Visual!");
-    if (aUseAlpha || useWebRender) {
+    if (aUseAlpha) {
       // We try to use a fallback alpha visual
       GdkScreen* screen = gtk_widget_get_screen(mShell);
       gdkVisual = gdk_screen_get_rgba_visual(screen);