gpu: Bind dummy GL API when no context is current

ui/gl/gl_context_osmesa.cc

Index: ui/gl/gl_context_osmesa.cc
diff --git a/ui/gl/gl_context_osmesa.cc b/ui/gl/gl_context_osmesa.cc
index e7ccba99039c116727f7c9f4061ad6adea717c0e..28172f7b17e8ceefbd5a3edbd4b94dc7af9ae01e 100644
--- a/ui/gl/gl_context_osmesa.cc
+++ b/ui/gl/gl_context_osmesa.cc
@@ -69,8 +69,9 @@ bool GLContextOSMesa::MakeCurrent(GLSurface* surface) {
   OSMesaPixelStore(OSMESA_Y_UP, 0);
 
   SetCurrent(surface);
+  ScopedReleaseCurrent release_current(this, surface);
+
   if (!InitializeDynamicBindings()) {
-    ReleaseCurrent(surface);
     return false;
   }
 
@@ -79,6 +80,7 @@ bool GLContextOSMesa::MakeCurrent(GLSurface* surface) {
     return false;
   }
 
+  release_current.Release();
   return true;
 }