Add support for setting TrackStart on solid color 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/solid_color_scrollbar_layer_impl.h"
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/test/test_shared_bitmap_manager.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cc {
 namespace {
 
 class ScrollbarAnimationControllerLinearFadeTest : public testing::Test {
  public:
   ScrollbarAnimationControllerLinearFadeTest()
       : host_impl_(&proxy_, &shared_bitmap_manager_) {}
 
  protected:
   virtual void SetUp() {
     const int kThumbThickness = 10;
+    const int kTrackStart = 0;
     const bool kIsLeftSideVerticalScrollbar = false;
     const bool kIsOverlayScrollbar = true;  // Allow opacity animations.
 
     scoped_ptr<LayerImpl> scroll_layer =
         LayerImpl::Create(host_impl_.active_tree(), 1);
     scrollbar_layer_ =
         SolidColorScrollbarLayerImpl::Create(host_impl_.active_tree(),
                                              2,
                                              HORIZONTAL,
                                              kThumbThickness,
+                                             kTrackStart,
                                              kIsLeftSideVerticalScrollbar,
                                              kIsOverlayScrollbar);
     clip_layer_ = LayerImpl::Create(host_impl_.active_tree(), 3);
     scroll_layer->SetScrollClipLayer(clip_layer_->id());
     LayerImpl* scroll_layer_ptr = scroll_layer.get();
     clip_layer_->AddChild(scroll_layer.Pass());
 
     scrollbar_layer_->SetClipLayerById(clip_layer_->id());
     scrollbar_layer_->SetScrollLayerById(scroll_layer_ptr->id());
     clip_layer_->SetBounds(gfx::Size(100, 100));
@@ skipping 211 matching lines @@
   EXPECT_FLOAT_EQ(1, scrollbar_layer_->opacity());
 
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->DidScrollGestureEnd(time);
   EXPECT_TRUE(scrollbar_controller_->IsAnimating());
   EXPECT_FLOAT_EQ(1, scrollbar_layer_->opacity());
 }
 
 }  // namespace
 }  // namespace cc