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

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

Index: ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc b/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
index da0638ae29a992077fd84884a1816b8eb5722bff..c3952bddc6c3ead34a6e08b1b9e7cd2abb0ba722 100644
--- a/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
@@ -112,8 +112,7 @@ scoped_refptr<ui::NativePixmap> GbmSurfaceFactory::CreateNativePixmap(
 #if !defined(OS_CHROMEOS)
   // Support for memory mapping accelerated buffers requires some
   // CrOS-specific patches (using vgem).
-  if (usage != SCANOUT)
-    return nullptr;
+  DCHECK_EQ(gfx::BufferUsage::SCANOUT, usage);
 #endif
 
   scoped_refptr<GbmDevice> gbm = GetGbmDevice(widget);
@@ -136,20 +135,6 @@ bool GbmSurfaceFactory::CanShowPrimaryPlaneAsOverlay() {
   return allow_surfaceless_;
 }
 
-bool GbmSurfaceFactory::CanCreateNativePixmap(gfx::BufferUsage usage) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  switch (usage) {
-    case gfx::BufferUsage::MAP:
-      return false;
-    case gfx::BufferUsage::PERSISTENT_MAP:
-      return false;
-    case gfx::BufferUsage::SCANOUT:
-      return true;
-  }
-  NOTREACHED();
-  return false;
-}
-
 scoped_refptr<GbmDevice> GbmSurfaceFactory::GetGbmDevice(
     gfx::AcceleratedWidget widget) {
   return static_cast<GbmDevice*>(