Properly initialize top controls content offset on LayerTreeHost.

cc/trees/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/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 255 matching lines @@
       shared_bitmap_manager_(manager),
       id_(id),
       transfer_buffer_memory_limit_(0u) {
   DCHECK(proxy_->IsImplThread());
   DidVisibilityChange(this, visible_);
   animation_registrar_->set_supports_scroll_animations(
       proxy_->SupportsImplScrolling());
 
   SetDebugState(settings.initial_debug_state);
 
+  // LTHI always has an active tree.
+  active_tree_ = LayerTreeImpl::create(this);
+  TRACE_EVENT_OBJECT_CREATED_WITH_ID(
+      TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
+
   if (settings.calculate_top_controls_position) {
     top_controls_manager_ =
         TopControlsManager::Create(this,
                                    settings.top_controls_height,
                                    settings.top_controls_show_threshold,
                                    settings.top_controls_hide_threshold);
   }
-
-  SetDebugState(settings.initial_debug_state);
-
-  // LTHI always has an active tree.
-  active_tree_ = LayerTreeImpl::create(this);
-  TRACE_EVENT_OBJECT_CREATED_WITH_ID(
-      TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
 }
 
 LayerTreeHostImpl::~LayerTreeHostImpl() {
   DCHECK(proxy_->IsImplThread());
   TRACE_EVENT0("cc", "LayerTreeHostImpl::~LayerTreeHostImpl()");
   TRACE_EVENT_OBJECT_DELETED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
 
   if (input_handler_client_) {
     input_handler_client_->WillShutdown();
@@ skipping 1387 matching lines @@
 }
 
 void LayerTreeHostImpl::UpdateInnerViewportContainerSize() {
   LayerImpl* container_layer = active_tree_->InnerViewportContainerLayer();
   if (!container_layer)
     return;
 
   if (top_controls_manager_) {
     container_layer->SetBoundsDelta(
         gfx::Vector2dF(0, active_tree_->top_controls_layout_height() -
-            active_tree_->total_top_controls_top_offset() -
-            top_controls_manager_->controls_height()));
+            active_tree_->total_top_controls_content_offset()));
   }
 }
 
 void LayerTreeHostImpl::SetTopControlsLayoutHeight(float height) {
   if (active_tree_->top_controls_layout_height() == height)
     return;
 
   active_tree_->set_top_controls_layout_height(height);
   UpdateInnerViewportContainerSize();
   SetFullRootLayerDamage();
@@ skipping 105 matching lines @@
     // tree, rename the pending tree the recycle tree so we can reuse it on the
     // next sync.
     DCHECK(!recycle_tree_);
     pending_tree_.swap(recycle_tree_);
 
     active_tree_->SetRootLayerScrollOffsetDelegate(
         root_layer_scroll_offset_delegate_);
 
     if (top_controls_manager_) {
       top_controls_manager_->SetControlsTopOffset(
-          active_tree_->total_top_controls_top_offset());
+          active_tree_->total_top_controls_content_offset() -
+          top_controls_manager_->top_controls_height());
     }
 
     UpdateInnerViewportContainerSize();
   } else {
     active_tree_->ProcessUIResourceRequestQueue();
   }
 
   active_tree_->DidBecomeActive();
   ActivateAnimations();
   if (settings_.impl_side_painting)
@@ skipping 388 matching lines @@
 
 void LayerTreeHostImpl::DidChangeTopControlsPosition() {
   UpdateInnerViewportContainerSize();
   SetNeedsRedraw();
   SetNeedsAnimate();
   active_tree_->set_needs_update_draw_properties();
   SetFullRootLayerDamage();
 }
 
 void LayerTreeHostImpl::SetControlsTopOffset(float offset) {
-  active_tree_->set_top_controls_delta(
-      offset - active_tree_->top_controls_top_offset());
+  float current_top_offset = active_tree_->top_controls_content_offset() -
+      top_controls_manager_->top_controls_height();
+  active_tree_->set_top_controls_delta(offset - current_top_offset);
 }
 
 float LayerTreeHostImpl::ControlsTopOffset() const {
-  return active_tree_->total_top_controls_top_offset();
+  return active_tree_->total_top_controls_content_offset() -
+      top_controls_manager_->top_controls_height();
 }
 
 void LayerTreeHostImpl::BindToClient(InputHandlerClient* client) {
   DCHECK(input_handler_client_ == NULL);
   input_handler_client_ = client;
 }
 
 static LayerImpl* NextScrollLayer(LayerImpl* layer) {
   if (LayerImpl* scroll_parent = layer->scroll_parent())
     return scroll_parent;
@@ skipping 1129 matching lines @@
 }
 
 void LayerTreeHostImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
   std::vector<PictureLayerImpl*>::iterator it =
       std::find(picture_layers_.begin(), picture_layers_.end(), layer);
   DCHECK(it != picture_layers_.end());
   picture_layers_.erase(it);
 }
 
 }  // namespace cc