cc : Initialize solid color scrollbar layer on main thread to 0.

cc/trees/layer_tree_host_impl_unittest.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 2660 matching lines @@
     host_impl_->InitializeRenderer(output_surface_.get());
 
     SetupScrollAndContentsLayers(content_size);
     host_impl_->active_tree()->PushPageScaleFromMainThread(1.f, 1.f, 4.f);
     host_impl_->SetViewportSize(
         gfx::Size(content_size.width() / 2, content_size.height() / 2));
 
     std::unique_ptr<SolidColorScrollbarLayerImpl> scrollbar =
         SolidColorScrollbarLayerImpl::Create(host_impl_->active_tree(), 400,
                                              VERTICAL, 10, 0, false, true);
+    scrollbar->SetOpacity(0.f);
     EXPECT_FLOAT_EQ(0.f, scrollbar->opacity());
 
     LayerImpl* scroll = host_impl_->active_tree()->OuterViewportScrollLayer();
     LayerImpl* root = host_impl_->active_tree()->InnerViewportContainerLayer();
     scrollbar->SetScrollLayerId(scroll->id());
     root->AddChild(std::move(scrollbar));
 
     host_impl_->active_tree()->DidBecomeActive();
     SetNeedsRebuildPropertyTrees();
     DrawFrame();
@@ skipping 164 matching lines @@
     settings.scrollbar_fade_delay_ms = 20;
     settings.scrollbar_fade_duration_ms = 20;
     gfx::Size content_size(100, 100);
 
     CreateHostImpl(settings, CreateOutputSurface());
     host_impl_->CreatePendingTree();
     CreateScrollAndContentsLayers(host_impl_->pending_tree(), content_size);
     std::unique_ptr<SolidColorScrollbarLayerImpl> scrollbar =
         SolidColorScrollbarLayerImpl::Create(host_impl_->pending_tree(), 400,
                                              VERTICAL, 10, 0, false, true);
+    scrollbar->SetOpacity(0.f);
     LayerImpl* scroll = host_impl_->pending_tree()->OuterViewportScrollLayer();
     LayerImpl* root = host_impl_->pending_tree()->InnerViewportContainerLayer();
     scrollbar->SetScrollLayerId(scroll->id());
     root->AddChild(std::move(scrollbar));
     host_impl_->pending_tree()->PushPageScaleFromMainThread(1.f, 1.f, 1.f);
     host_impl_->pending_tree()->BuildPropertyTreesForTesting();
     host_impl_->ActivateSyncTree();
 
     LayerImpl* scrollbar_layer = host_impl_->active_tree()->LayerById(400);
 
@@ skipping 7875 matching lines @@
 
   // Re-initialize with a software output surface.
   output_surface_ = FakeOutputSurface::CreateSoftware(
       base::WrapUnique(new SoftwareOutputDevice));
   host_impl_->InitializeRenderer(output_surface_.get());
   EXPECT_FALSE(host_impl_->use_gpu_rasterization());
 }
 
 }  // namespace
 }  // namespace cc