ozone: Introduce ClientPixmap and ClientPixmapFactory for non-GPU processes.

ui/ozone/platform/drm/host/drm_display_host_manager.h

Index: ui/ozone/platform/drm/host/drm_display_host_manager.h
diff --git a/ui/ozone/platform/drm/host/drm_display_host_manager.h b/ui/ozone/platform/drm/host/drm_display_host_manager.h
index 5f14cf35b87cf784edd08d29e2f0092924a3c963..721707936e5d2120e09ed1475230bc02ec4d56da 100644
--- a/ui/ozone/platform/drm/host/drm_display_host_manager.h
+++ b/ui/ozone/platform/drm/host/drm_display_host_manager.h
@@ -8,6 +8,7 @@
 #include <queue>
 #include <set>
 
+#include "base/file_descriptor_posix.h"
 #include "base/files/scoped_file.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
@@ -44,6 +45,8 @@ class DrmDisplayHostManager : public DeviceEventObserver,
   void RelinquishDisplayControl(const DisplayControlCallback& callback);
   void UpdateDisplays(const GetDisplaysCallback& callback);
 
+  base::FileDescriptor DupVgemFd();
+
   // DeviceEventObserver overrides:
   void OnDeviceEvent(const DeviceEvent& event) override;