Allow changing top controls height

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 bb1be9856d093663f5533a2c4a6cff40c0a50cfd..7e6f94bb93aea106fb2c3c85f168e9d8a6af93d1 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -259,7 +259,6 @@ LayerTreeHostImpl::LayerTreeHostImpl(
   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);
 
@@ -1633,9 +1632,13 @@ void LayerTreeHostImpl::UpdateViewportContainerSizes() {
 
   // Adjust the inner viewport by shrinking/expanding the container to account
   // for the change in top controls height since the last Resize from Blink.
+  float top_controls_layout_height =
+      active_tree_->top_controls_shrink_blink_size()
+          ? active_tree_->top_controls_height()
+          : 0.f;
   inner_container->SetBoundsDelta(
-      gfx::Vector2dF(0, active_tree_->top_controls_layout_height() -
-          active_tree_->total_top_controls_content_offset()));
+      gfx::Vector2dF(0, top_controls_layout_height -
+                            active_tree_->total_top_controls_content_offset()));
 
   if (!outer_container || outer_container->BoundsForScrolling().IsEmpty())
     return;
@@ -1658,11 +1661,24 @@ void LayerTreeHostImpl::UpdateViewportContainerSizes() {
   anchor.ResetViewportToAnchoredPosition();
 }
 
-void LayerTreeHostImpl::SetTopControlsLayoutHeight(float height) {
-  if (active_tree_->top_controls_layout_height() == height)
+void LayerTreeHostImpl::SetTopControlsHeight(float height) {
+  if (active_tree_->top_controls_height() == height)
     return;
 
-  active_tree_->set_top_controls_layout_height(height);
+  // Adjust the delta to maintain the current top controls offset.
+  active_tree_->set_top_controls_delta(active_tree_->top_controls_delta() -
+                                       active_tree_->top_controls_height() +
+                                       height);
+  active_tree_->set_top_controls_height(height);
+  UpdateViewportContainerSizes();
+  SetFullRootLayerDamage();
+}
+
+void LayerTreeHostImpl::SetTopControlsShrinkBlinkSize(bool shrink) {
+  if (active_tree_->top_controls_shrink_blink_size() == shrink)
+    return;
+
+  active_tree_->set_top_controls_shrink_blink_size(shrink);
   UpdateViewportContainerSizes();
   SetFullRootLayerDamage();
 }
@@ -1777,6 +1793,8 @@ void LayerTreeHostImpl::ActivateSyncTree() {
         root_layer_scroll_offset_delegate_);
 
     if (top_controls_manager_) {
+      top_controls_manager_->SetTopControlsHeight(
+          active_tree_->top_controls_height());
       top_controls_manager_->SetControlsTopOffset(
           active_tree_->total_top_controls_content_offset() -
           top_controls_manager_->top_controls_height());
@@ -2242,13 +2260,13 @@ void LayerTreeHostImpl::DidChangeTopControlsPosition() {
 
 void LayerTreeHostImpl::SetControlsTopOffset(float offset) {
   float current_top_offset = active_tree_->top_controls_content_offset() -
-      top_controls_manager_->top_controls_height();
+                             active_tree_->top_controls_height();
   active_tree_->set_top_controls_delta(offset - current_top_offset);
 }
 
 float LayerTreeHostImpl::ControlsTopOffset() const {
   return active_tree_->total_top_controls_content_offset() -
-      top_controls_manager_->top_controls_height();
+         active_tree_->top_controls_height();
 }
 
 void LayerTreeHostImpl::BindToClient(InputHandlerClient* client) {