Make IsSolidColor() a property on CC scrollbar layers.

cc/animation/scrollbar_animation_controller_linear_fade_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 "cc/animation/scrollbar_animation_controller_linear_fade.h"
 
 #include "cc/layers/scrollbar_layer_impl.h"
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/trees/single_thread_proxy.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cc {
 namespace {
 
 class ScrollbarAnimationControllerLinearFadeTest : public testing::Test {
  public:
   ScrollbarAnimationControllerLinearFadeTest() : host_impl_(&proxy_) {}
 
  protected:
   virtual void SetUp() {
     scroll_layer_ = LayerImpl::Create(host_impl_.active_tree(), 1);
     scrollbar_layer_ = ScrollbarLayerImpl::Create(
-        host_impl_.active_tree(), 2, HORIZONTAL);
+        host_impl_.active_tree(), 2, HORIZONTAL, false);
 
     scroll_layer_->SetMaxScrollOffset(gfx::Vector2d(50, 50));
     scroll_layer_->SetBounds(gfx::Size(50, 50));
     scroll_layer_->SetHorizontalScrollbarLayer(scrollbar_layer_.get());
 
     scrollbar_controller_ = ScrollbarAnimationControllerLinearFade::Create(
         scroll_layer_.get(),
         base::TimeDelta::FromSeconds(2),
         base::TimeDelta::FromSeconds(3));
   }
@@ skipping 118 matching lines @@
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(1.0f / 3.0f, scrollbar_layer_->opacity());
 
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->opacity());
 }
 
 }  // namespace
 }  // namespace cc