[cc] Make LayerImpls point at LayerTreeImpl instead of LTHI

cc/layer_tree_host_impl.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/layer_tree_host_impl.h"
 
 #include <algorithm>
 
 #include "base/basictypes.h"
 #include "base/debug/trace_event.h"
 #include "base/json/json_writer.h"
 #include "cc/append_quads_data.h"
 #include "cc/damage_tracker.h"
 #include "cc/debug_rect_history.h"
 #include "cc/delay_based_time_source.h"
 #include "cc/delegating_renderer.h"
 #include "cc/frame_rate_counter.h"
 #include "cc/gl_renderer.h"
 #include "cc/heads_up_display_layer_impl.h"
 #include "cc/layer_iterator.h"
 #include "cc/layer_tree_host.h"
 #include "cc/layer_tree_host_common.h"
+#include "cc/layer_tree_impl.h"
 #include "cc/math_util.h"
 #include "cc/overdraw_metrics.h"
 #include "cc/page_scale_animation.h"
 #include "cc/prioritized_resource_manager.h"
 #include "cc/quad_culler.h"
 #include "cc/render_pass_draw_quad.h"
 #include "cc/rendering_stats.h"
 #include "cc/scrollbar_animation_controller.h"
 #include "cc/scrollbar_layer_impl.h"
 #include "cc/shared_quad_state.h"
@@ skipping 915 matching lines @@
 {
     m_client->onSwapBuffersCompleteOnImplThread();
 }
 
 void LayerTreeHostImpl::readback(void* pixels, const gfx::Rect& rect)
 {
     DCHECK(m_renderer);
     m_renderer->getFramebufferPixels(pixels, rect);
 }
 
+LayerImpl* LayerTreeHostImpl::rootLayer() const
+{
+  return m_activeTree->RootLayer();
+}
+
+LayerImpl* LayerTreeHostImpl::rootScrollLayer() const
+{
+  return m_activeTree->root_scroll_layer();
+}
+
+LayerImpl* LayerTreeHostImpl::currentlyScrollingLayer() const
+{
+  return m_activeTree->currently_scrolling_layer();
+}
+
 // Content layers can be either directly scrollable or contained in an outer
 // scrolling layer which applies the scroll transform. Given a content layer,
 // this function returns the associated scroll layer if any.
 static LayerImpl* findScrollLayerForContentLayer(LayerImpl* layerImpl)
 {
     if (!layerImpl)
         return 0;
 
     if (layerImpl->scrollable())
         return layerImpl;
@@ skipping 736 matching lines @@
     ScrollbarAnimationController* scrollbarController = layer->scrollbarAnimationController();
     double monotonicTime = (time - base::TimeTicks()).InSecondsF();
     if (scrollbarController && scrollbarController->animate(monotonicTime))
         m_client->setNeedsRedrawOnImplThread();
 
     for (size_t i = 0; i < layer->children().size(); ++i)
         animateScrollbarsRecursive(layer->children()[i], time);
 }
 
 }  // namespace cc