Makes copying layers clone external textures.

content/browser/web_contents/web_contents_view_aura.cc

Index: content/browser/web_contents/web_contents_view_aura.cc
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index 6efcea69055ddda06f7a2d84a7ff7517565d8f6b..7d19edba5beb58f06ce2011af32432d8f5532227 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -547,6 +547,13 @@ bool WebContentsViewAura::HasHitTestMask() const {
 void WebContentsViewAura::GetHitTestMask(gfx::Path* mask) const {
 }
 
+scoped_refptr<ui::Texture> WebContentsViewAura::CopyTexture() {
+  // The layer we create doesn't have an external texture, so this should never
+  // get invoked.
+  NOTREACHED();
+  return scoped_refptr<ui::Texture>();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // WebContentsViewAura, ui::EventHandler implementation: