Find root scroll layer at tree activation

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"
@@ skipping 872 matching lines @@
 {
     m_client->onSwapBuffersCompleteOnImplThread();
 }
 
 void LayerTreeHostImpl::readback(void* pixels, const gfx::Rect& rect)
 {
     DCHECK(m_renderer);
     m_renderer->getFramebufferPixels(pixels, rect);
 }
 
+bool LayerTreeHostImpl::haveRootScrollLayer() const {
+  return rootScrollLayer();
+}
+
+float LayerTreeHostImpl::rootScrollLayerTotalScrollY() const {
+  if (LayerImpl* layer = rootScrollLayer())
+    return layer->scrollOffset().y() + layer->scrollDelta().y();
+  return 0.0f;
+}
+
 LayerImpl* LayerTreeHostImpl::rootLayer() const
 {
   return m_activeTree->RootLayer();
 }
 
 LayerImpl* LayerTreeHostImpl::rootScrollLayer() const
 {
-  return m_activeTree->root_scroll_layer();
+  return m_activeTree->RootScrollLayer();
 }
 
 LayerImpl* LayerTreeHostImpl::currentlyScrollingLayer() const
 {
-  return m_activeTree->currently_scrolling_layer();
+  return m_activeTree->CurrentlyScrollingLayer();
 }
 
 // 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;
 
     if (layerImpl->drawsContent() && layerImpl->parent() && layerImpl->parent()->scrollable())
         return layerImpl->parent();
 
     return 0;
 }
 
-LayerTreeImpl* LayerTreeHostImpl::activeTree()
-{
-    return m_activeTree.get();
-}
-
 void LayerTreeHostImpl::createPendingTree()
 {
     CHECK(!m_pendingTree);
     m_pendingTree = LayerTreeImpl::create(this);
     m_client->onCanDrawStateChanged(canDraw());
     m_client->onHasPendingTreeStateChanged(pendingTree());
 }
 
 void LayerTreeHostImpl::checkForCompletedTextures()
 {
@@ skipping 476 matching lines @@
 
 void LayerTreeHostImpl::makeScrollAndScaleSet(ScrollAndScaleSet* scrollInfo, gfx::Vector2d scrollOffset, float pageScale)
 {
     if (!rootScrollLayer())
         return;
 
     LayerTreeHostCommon::ScrollUpdateInfo scroll;
     scroll.layerId = rootScrollLayer()->id();
     scroll.scrollDelta = scrollOffset - rootScrollLayer()->scrollOffset();
     scrollInfo->scrolls.push_back(scroll);
-    activeTree()->root_scroll_layer()->setSentScrollDelta(scroll.scrollDelta);
+    activeTree()->RootScrollLayer()->setSentScrollDelta(scroll.scrollDelta);
     scrollInfo->pageScaleDelta = pageScale / m_pinchZoomViewport.page_scale_factor();
     m_pinchZoomViewport.set_sent_page_scale_delta(scrollInfo->pageScaleDelta);
 }
 
 static void collectScrollDeltas(ScrollAndScaleSet* scrollInfo, LayerImpl* layerImpl)
 {
     if (!layerImpl)
         return;
 
     if (!layerImpl->scrollDelta().IsZero()) {
@@ skipping 235 matching lines @@
     LayerImpl* layer = getNonCompositedContentLayerRecursive(tree->RootLayer());
     return layer ? layer->getPicture() : skia::RefPtr<SkPicture>();
 }
 
 void LayerTreeHostImpl::savePaintTime(const base::TimeDelta& totalPaintTime)
 {
     m_paintTimeCounter->SavePaintTime(totalPaintTime);
 }
 
 }  // namespace cc