ozone: Avoid scheduling an invalid framebuffer

AddFramebuffer2 can fail for buffers coming via exo.
We should not use an invalid fb when pageflipping in those cases
otherwise the GPU process will crash.

Bug: 779356
Test: wayland_simple_client with crrev.com/c/1056018
Change-Id: I179ce2ddbe1fb5080f9d00989ccf96ddf3f94d68
Reviewed-on: https://chromium-review.googlesource.com/1056017Reviewed-by: David Reveman <reveman@chromium.org>
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558140}

ui/ozone/platform/drm/gpu/gbm_buffer.cc

@@ -390,9 +390,11 @@ bool GbmPixmap::ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                                      gfx::GpuFence* gpu_fence) {
   DCHECK(buffer_->GetFlags() & GBM_BO_USE_SCANOUT);
 
-  surface_manager_->GetSurface(widget)->QueueOverlayPlane(
-      OverlayPlane(buffer_, plane_z_order, plane_transform, display_bounds,
-                   crop_rect, enable_blend, base::kInvalidPlatformFile));
+  if (buffer_->GetFramebufferId()) {
+    surface_manager_->GetSurface(widget)->QueueOverlayPlane(
+        OverlayPlane(buffer_, plane_z_order, plane_transform, display_bounds,
+                     crop_rect, enable_blend, base::kInvalidPlatformFile));
+  }
 
   return true;
 }