Bug 1859591 - Add gfxCriticalNote when failing to load EGL/GLES DLLs on Windows. r=gfx-reviewers,jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D191206

gfx/gl/GLLibraryEGL.cpp

@@ -24,6 +24,7 @@
 #ifdef XP_WIN
 #  include "mozilla/gfx/DeviceManagerDx.h"
 #  include "nsWindowsHelpers.h"
+#  include "prerror.h"
 
 #  include <d3d11.h>
 #endif
@@ -150,7 +151,12 @@ static PRLibrary* LoadLibraryForEGLOnWindows(const nsAString& filename) {
   PRLibSpec lspec;
   lspec.type = PR_LibSpec_PathnameU;
   lspec.value.pathname_u = path.get();
-  return PR_LoadLibraryWithFlags(lspec, PR_LD_LAZY | PR_LD_LOCAL);
+  PRLibrary* lib = PR_LoadLibraryWithFlags(lspec, PR_LD_LAZY | PR_LD_LOCAL);
+  if (!lib) {
+    gfxCriticalNote << "Failed to load " << path.get() << " " << PR_GetError()
+                    << " " << PR_GetOSError();
+  }
+  return lib;
 }
 
 #endif  // XP_WIN