Replace scoped_ptr with std::unique_ptr in //ui

R=sadrul, sky
TBR=bshe,aelias,rockot,piman,achuith,reveman
BUG=554298
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1868363002

Cr-Commit-Position: refs/heads/master@{#386812}
diff --git a/ui/accessibility/ax_node_data.h b/ui/accessibility/ax_node_data.h
index 067adaa..e372f1d 100644
--- a/ui/accessibility/ax_node_data.h
+++ b/ui/accessibility/ax_node_data.h
@@ -124,7 +124,7 @@
   // takes up a fair amount of space. The assignment operator and copy
   // constructor both make a duplicate of the owned pointer, so it acts more
   // like a member than a pointer.
-  scoped_ptr<gfx::Transform> transform;
+  std::unique_ptr<gfx::Transform> transform;
 };
 
 }  // namespace ui