Aura: Keep the external texture until we've updated compositor references to it.

BUG=170229
TEST=by hand as per repro on bug

Review URL: https://codereview.chromium.org/13972011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@194647 0039d316-1c4b-4281-b951-d872f2087c98

ui/compositor/layer.cc

@@ -487,6 +487,10 @@ void Layer::SwitchCCLayerForTest() {
 }
 
 void Layer::SetExternalTexture(Texture* texture) {
+  // Hold a ref to the old |Texture| until we have updated all
+  // compositor references to the texture id that it holds.
+  scoped_refptr<ui::Texture> old_texture = texture_;
+
   DCHECK_EQ(type_, LAYER_TEXTURED);
   DCHECK(!solid_color_layer_);
   bool has_texture = !!texture;