Remove external begin frame source parameter and settings

cc/layers/scrollbar_layer_unittest.cc

 // Copyright 2012 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 <stddef.h>
 
 #include <unordered_map>
 
 #include "base/threading/thread_task_runner_handle.h"
 #include "cc/animation/animation_host.h"
@@ skipping 109 matching lines @@
     std::unique_ptr<FakeResourceTrackingUIResourceManager>
         fake_ui_resource_manager =
             base::MakeUnique<FakeResourceTrackingUIResourceManager>();
     fake_ui_resource_manager_ = fake_ui_resource_manager.get();
 
     layer_tree_host_.reset(new FakeLayerTreeHost(
         &fake_client_, &params, CompositorMode::SINGLE_THREADED));
     layer_tree_host_->SetUIResourceManagerForTesting(
         std::move(fake_ui_resource_manager));
     layer_tree_host_->InitializeSingleThreaded(
-        &single_thread_client_, base::ThreadTaskRunnerHandle::Get(), nullptr);
+        &single_thread_client_, base::ThreadTaskRunnerHandle::Get());
     layer_tree_ = layer_tree_host_->GetLayerTree();
     layer_tree_host_->SetVisible(true);
     fake_client_.SetLayerTreeHost(layer_tree_host_.get());
   }
 
   LayerImpl* LayerImplForScrollAreaAndScrollbar(
       FakeLayerTreeHost* host,
       std::unique_ptr<Scrollbar> scrollbar,
       bool reverse_order,
       bool use_solid_color_scrollbar,
@@ skipping 978 matching lines @@
   TestScale(gfx::Rect(1240, 0, 15, 1333), 2.7754839f);
   TestScale(gfx::Rect(1240, 0, 15, 677), 2.46677136f);
 
   // Horizontal Scrollbars.
   TestScale(gfx::Rect(0, 1240, 1333, 15), 2.7754839f);
   TestScale(gfx::Rect(0, 1240, 677, 15), 2.46677136f);
 }
 
 }  // namespace
 }  // namespace cc