Fix bug whereby OnGpuSwitched was never called

gpu/config/gpu_info.h

Index: gpu/config/gpu_info.h
diff --git a/gpu/config/gpu_info.h b/gpu/config/gpu_info.h
index 9460724aded25debe993005a97d16f9a632746b3..8331c5820866b03a1c723a6f134c5acd79a4ad11 100644
--- a/gpu/config/gpu_info.h
+++ b/gpu/config/gpu_info.h
@@ -143,6 +143,9 @@ struct GPU_EXPORT GPUInfo {
   // Secondary GPUs, for example, the integrated GPU in a dual GPU machine.
   std::vector<GPUDevice> secondary_gpus;
 
+  // The currently active gpu.
+  const GPUDevice& active_gpu() const;
+
   // The vendor of the graphics driver currently installed.
   std::string driver_vendor;