Mac: Only allow NSOpenGLContext displaying on the main display

content/common/gpu/image_transport_surface_fbo_mac.mm

Index: content/common/gpu/image_transport_surface_fbo_mac.mm
diff --git a/content/common/gpu/image_transport_surface_fbo_mac.mm b/content/common/gpu/image_transport_surface_fbo_mac.mm
index ec827c2e47ad7f2064a53bcd204417e7da251b54..e30a42a283f73d348bac4cbbeb1ac5ac34a32274 100644
--- a/content/common/gpu/image_transport_surface_fbo_mac.mm
+++ b/content/common/gpu/image_transport_surface_fbo_mac.mm
@@ -180,7 +180,11 @@ bool ImageTransportSurfaceFBO::SwapBuffersInternal() {
   DCHECK(backbuffer_suggested_allocation_);
   if (!frontbuffer_suggested_allocation_)
     return true;
-  glFlush();
+
+  {
+    TRACE_EVENT0("gpu", "ImageTransportSurfaceFBO::glFlush");
+    glFlush();
+  }
 
   // It is the responsibility of the storage provider to send the swap IPC.
   is_swap_buffers_send_pending_ = true;