Bug 1449205 - Share OpenGL contexts between WebRender windows on macOS. r=sotaro

Differential Revision: https://phabricator.services.mozilla.com/D53121

gfx/webrender_bindings/RenderCompositorOGL.cpp

@@ -9,6 +9,7 @@
 #include "GLContext.h"
 #include "GLContextProvider.h"
 #include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/webrender/RenderThread.h"
 #include "mozilla/widget/CompositorWidget.h"
 
 namespace mozilla {
@@ -17,9 +18,11 @@ namespace wr {
 /* static */
 UniquePtr<RenderCompositor> RenderCompositorOGL::Create(
     RefPtr<widget::CompositorWidget>&& aWidget) {
-  RefPtr<gl::GLContext> gl;
-  gl = gl::GLContextProvider::CreateForCompositorWidget(
-      aWidget, /* aWebRender */ true, /* aForceAccelerated */ true);
+  RefPtr<gl::GLContext> gl = RenderThread::Get()->SharedGL();
+  if (!gl) {
+    gl = gl::GLContextProvider::CreateForCompositorWidget(
+        aWidget, /* aWebRender */ true, /* aForceAccelerated */ true);
+  }
   if (!gl || !gl->MakeCurrent()) {
     gfxCriticalNote << "Failed GL context creation for WebRender: "
                     << gfx::hexa(gl.get());

gfx/webrender_bindings/RenderThread.cpp

@@ -952,6 +952,16 @@ static already_AddRefed<gl::GLContext> CreateGLContextEGL() {
 }
 #endif
 
+#ifdef XP_MACOSX
+static already_AddRefed<gl::GLContext> CreateGLContextCGL() {
+  nsCString failureUnused;
+  return gl::GLContextProvider::CreateHeadless(
+      gl::CreateContextFlags::ALLOW_OFFLINE_RENDERER |
+          gl::CreateContextFlags::FORCE_ENABLE_HARDWARE,
+      &failureUnused);
+}
+#endif
+
 static already_AddRefed<gl::GLContext> CreateGLContext() {
 #ifdef XP_WIN
   if (gfx::gfxVars::UseWebRenderANGLE()) {
@@ -966,8 +976,11 @@ static already_AddRefed<gl::GLContext> CreateGLContext() {
     return CreateGLContextEGL();
   }
 #endif
-  // We currently only support a shared GLContext
-  // with ANGLE.
+
+#ifdef XP_MACOSX
+  return CreateGLContextCGL();
+#endif
+
   return nullptr;
 }