cc:: Change plumbing for external_begin_frame_source to the Scheduler.

cc/layers/layer_position_constraint_unittest.cc

 // Copyright 2013 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.
 
 #include "cc/layers/layer_position_constraint.h"
 
 #include <vector>
 
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
@@ skipping 59 matching lines @@
         root_impl_(nullptr),
         inner_viewport_container_layer_impl_(nullptr),
         scroll_layer_impl_(nullptr),
         outer_viewport_container_layer_impl_(nullptr),
         child_transform_layer_impl_(nullptr),
         child_impl_(nullptr),
         grand_child_impl_(nullptr),
         great_grand_child_impl_(nullptr) {
     layer_tree_host_->InitializeForTesting(
         TaskRunnerProvider::Create(nullptr, nullptr),
-        scoped_ptr<Proxy>(new FakeProxy));
+        scoped_ptr<Proxy>(new FakeProxy), nullptr);
     CreateTreeForTest();
     fixed_to_top_left_.set_is_fixed_position(true);
     fixed_to_bottom_right_.set_is_fixed_position(true);
     fixed_to_bottom_right_.set_is_fixed_to_right_edge(true);
     fixed_to_bottom_right_.set_is_fixed_to_bottom_edge(true);
   }
 
   void CreateTreeForTest() {
     // scroll_layer_ is the inner viewport scroll layer and child_ is the outer
     // viewport scroll layer.
@@ skipping 1064 matching lines @@
   VerifySerializeAndDeserializeProto(true, false, true);
   VerifySerializeAndDeserializeProto(true, false, false);
   VerifySerializeAndDeserializeProto(false, true, true);
   VerifySerializeAndDeserializeProto(false, true, false);
   VerifySerializeAndDeserializeProto(false, false, true);
   VerifySerializeAndDeserializeProto(false, false, false);
 }
 
 }  // namespace
 }  // namespace cc