Made Blink aware of top controls offset (Chromium-side)

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index e8d9142d8e8f160e054b87ca530c4f21ac75c7fa..65d12a8fb67243ab496ee7d43ac3021ebc1c94d4 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -249,7 +249,6 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       zero_budget_(false),
       device_scale_factor_(1.f),
       overhang_ui_resource_id_(0),
-      top_controls_layout_height_(0.f),
       resourceless_software_draw_(false),
       begin_impl_frame_interval_(BeginFrameArgs::DefaultInterval()),
       animation_registrar_(AnimationRegistrar::Create()),
@@ -1678,11 +1677,10 @@ void LayerTreeHostImpl::UpdateInnerViewportContainerSize() {
   if (!container_layer)
     return;
 
-  if (top_controls_manager_)
+  if (top_controls_manager_) {
     container_layer->SetBoundsDelta(
-        gfx::Vector2dF(0,
-                       top_controls_layout_height_ -
-                           top_controls_manager_->content_top_offset()));
+        gfx::Vector2dF(0, -active_tree_->top_controls_delta()));
+  }
 }
 
 void LayerTreeHostImpl::DidLoseOutputSurface() {
@@ -1791,6 +1789,11 @@ void LayerTreeHostImpl::ActivateSyncTree() {
 
     active_tree_->SetRootLayerScrollOffsetDelegate(
         root_layer_scroll_offset_delegate_);
+
+    top_controls_manager_->SetControlsTopOffset(
+        active_tree_->total_top_controls_content_offset()
+            - top_controls_manager_->top_controls_height());
+
     UpdateInnerViewportContainerSize();
   } else {
     active_tree_->ProcessUIResourceRequestQueue();
@@ -2146,16 +2149,6 @@ void LayerTreeHostImpl::SetViewportSize(const gfx::Size& device_viewport_size) {
   active_tree_->set_needs_update_draw_properties();
 }
 
-void LayerTreeHostImpl::SetTopControlsLayoutHeight(
-    float top_controls_layout_height) {
-  if (top_controls_layout_height_ == top_controls_layout_height)
-    return;
-  top_controls_layout_height_ = top_controls_layout_height;
-
-  UpdateInnerViewportContainerSize();
-  SetFullRootLayerDamage();
-}
-
 void LayerTreeHostImpl::SetOverhangUIResource(
     UIResourceId overhang_ui_resource_id,
     const gfx::Size& overhang_ui_resource_size) {
@@ -2201,6 +2194,10 @@ const gfx::Transform& LayerTreeHostImpl::DrawTransform() const {
 }
 
 void LayerTreeHostImpl::DidChangeTopControlsPosition() {
+  active_tree_->set_top_controls_delta(

[aelias_OOO_until_Jul13, 2014/08/29 04:37:01]

We end up holding a field with redundant information (can be fully inferred from
other existing fields), which I prefer to avoid.  How about making
top_controls_manager hold less state and instead call getters/setters that
manipulate the active tree?

[bokan, 2014/08/29 18:02:14]

sgtm

[bokan, 2014/09/02 18:57:16]

Done.

+      top_controls_manager_->content_top_offset() -
+          active_tree_->top_controls_content_offset());
+
   UpdateInnerViewportContainerSize();
   SetNeedsRedraw();
   SetNeedsAnimate();
@@ -2908,6 +2905,11 @@ scoped_ptr<ScrollAndScaleSet> LayerTreeHostImpl::ProcessScrollDeltas() {
   scroll_info->page_scale_delta = active_tree_->page_scale_delta();
   active_tree_->set_sent_page_scale_delta(scroll_info->page_scale_delta);
   scroll_info->swap_promises.swap(swap_promises_for_main_thread_scroll_update_);
+  scroll_info->top_controls_content_offset =
+      active_tree()->total_top_controls_content_offset();
+  active_tree_->set_sent_top_controls_delta(
+      scroll_info->top_controls_content_offset -
+          active_tree()->top_controls_content_offset());
 
   return scroll_info.Pass();
 }