Convert remaining scoped_ptr -> std::unique_ptr in //mojo/edk (minus js).

mojo/edk/embedder/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("../mojo_edk.gni")
 
 mojo_edk_source_set("embedder") {
   # This isn't really a standalone target; it must be linked into the
   # mojo_system_impl component.
   mojo_edk_visibility = [ "mojo/edk/system" ]
@@ skipping 27 matching lines @@
     ":platform",
   ]
 
   mojo_sdk_deps = [ "mojo/public/platform/native:system_impl_private_api" ]
 
   mojo_sdk_public_deps = [ "mojo/public/cpp/system" ]
 
   deps = [
     "//base",
   ]
+
+  mojo_edk_deps = [ "mojo/edk/util" ]
 }
 
 mojo_edk_source_set("platform") {
   # This isn't really a standalone target; it must be linked into the
   # mojo_system_impl component.
   visibility = [ ":embedder" ]
 
   mojo_edk_visibility = [
     "mojo/edk/system",
     "mojo/edk/system:test_utils",
@@ skipping 76 matching lines @@
     "//testing/gtest",
   ]
 
   mojo_edk_deps = [
     "mojo/edk/test:test_support",
     "mojo/edk/system",
     "mojo/edk/system:test_utils",
     "mojo/edk/util",
   ]
 }