(Reland) Always create top controls manager

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 9259b34743b8906fbee1a0ac5a63a78b38d5e5c0..a5cdc02734071d9c01977779467ff40b8184c4c4 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -241,12 +241,10 @@ LayerTreeHostImpl::LayerTreeHostImpl(
   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_show_threshold,
-                                   settings.top_controls_hide_threshold);
-  }
+  top_controls_manager_ =
+      TopControlsManager::Create(this,
+                                 settings.top_controls_show_threshold,
+                                 settings.top_controls_hide_threshold);
 }
 
 LayerTreeHostImpl::~LayerTreeHostImpl() {
@@ -916,8 +914,7 @@ DrawResult LayerTreeHostImpl::CalculateRenderPasses(
 }
 
 void LayerTreeHostImpl::MainThreadHasStoppedFlinging() {
-  if (top_controls_manager_)
-    top_controls_manager_->MainThreadHasStoppedFlinging();
+  top_controls_manager_->MainThreadHasStoppedFlinging();
   if (input_handler_client_)
     input_handler_client_->MainThreadHasStoppedFlinging();
 }
@@ -1423,12 +1420,10 @@ CompositorFrameMetadata LayerTreeHostImpl::MakeCompositorFrameMetadata() const {
   metadata.root_layer_size = active_tree_->ScrollableSize();
   metadata.min_page_scale_factor = active_tree_->min_page_scale_factor();
   metadata.max_page_scale_factor = active_tree_->max_page_scale_factor();
-  if (top_controls_manager_) {
-    metadata.location_bar_offset =
-        gfx::Vector2dF(0.f, top_controls_manager_->ControlsTopOffset());
-    metadata.location_bar_content_translation =
-        gfx::Vector2dF(0.f, top_controls_manager_->ContentTopOffset());
-  }
+  metadata.location_bar_offset =
+      gfx::Vector2dF(0.f, top_controls_manager_->ControlsTopOffset());
+  metadata.location_bar_content_translation =
+      gfx::Vector2dF(0.f, top_controls_manager_->ContentTopOffset());
 
   active_tree_->GetViewportSelection(&metadata.selection_start,
                                      &metadata.selection_end);
@@ -1658,9 +1653,21 @@ void LayerTreeHostImpl::UpdateViewportContainerSizes() {
   LayerImpl* inner_container = active_tree_->InnerViewportContainerLayer();
   LayerImpl* outer_container = active_tree_->OuterViewportContainerLayer();
 
-  if (!inner_container || !top_controls_manager_)
+  if (!inner_container)
     return;
 
+  // TODO(bokan): This code is currently specific to top controls. It should be
+  // made general. crbug.com/464814.
+  if (!TopControlsHeight()) {
+    if (outer_container)
+      outer_container->SetBoundsDelta(gfx::Vector2dF());
+
+    inner_container->SetBoundsDelta(gfx::Vector2dF());
+    active_tree_->InnerViewportScrollLayer()->SetBoundsDelta(gfx::Vector2dF());
+
+    return;
+  }
+
   ViewportAnchor anchor(InnerViewportScrollLayer(),
                         OuterViewportScrollLayer());
 
@@ -2361,8 +2368,7 @@ InputHandler::ScrollStatus LayerTreeHostImpl::ScrollBegin(
     InputHandler::ScrollInputType type) {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::ScrollBegin");
 
-  if (top_controls_manager_)
-    top_controls_manager_->ScrollBegin();
+  top_controls_manager_->ScrollBegin();
 
   DCHECK(!CurrentlyScrollingLayer());
   ClearCurrentlyScrollingLayer();
@@ -2573,9 +2579,6 @@ bool LayerTreeHostImpl::ShouldTopControlsConsumeScroll(
     const gfx::Vector2dF& scroll_delta) const {
   DCHECK(CurrentlyScrollingLayer());
 
-  if (!top_controls_manager_)
-    return false;
-
   // Always consume if it's in the direction to show the top controls.
   if (scroll_delta.y() < 0)
     return true;
@@ -2816,8 +2819,7 @@ void LayerTreeHostImpl::ClearCurrentlyScrollingLayer() {
 }
 
 void LayerTreeHostImpl::ScrollEnd() {
-  if (top_controls_manager_)
-    top_controls_manager_->ScrollEnd();
+  top_controls_manager_->ScrollEnd();
   ClearCurrentlyScrollingLayer();
 }
 
@@ -2938,8 +2940,7 @@ void LayerTreeHostImpl::PinchGestureBegin() {
     active_tree_->SetCurrentlyScrollingLayer(
         active_tree_->InnerViewportScrollLayer());
   }
-  if (top_controls_manager_)
-    top_controls_manager_->PinchBegin();
+  top_controls_manager_->PinchBegin();
 }
 
 void LayerTreeHostImpl::PinchGestureUpdate(float magnify_delta,
@@ -2998,8 +2999,7 @@ void LayerTreeHostImpl::PinchGestureEnd() {
     pinch_gesture_end_should_clear_scrolling_layer_ = false;
     ClearCurrentlyScrollingLayer();
   }
-  if (top_controls_manager_)
-    top_controls_manager_->PinchEnd();
+  top_controls_manager_->PinchEnd();
   client_->SetNeedsCommitOnImplThread();
   // When a pinch ends, we may be displaying content cached at incorrect scales,
   // so updating draw properties and drawing will ensure we are using the right
@@ -3094,7 +3094,7 @@ void LayerTreeHostImpl::AnimatePageScale(base::TimeTicks monotonic_time) {
 }
 
 void LayerTreeHostImpl::AnimateTopControls(base::TimeTicks time) {
-  if (!top_controls_manager_ || !top_controls_manager_->animation())
+  if (!top_controls_manager_->animation())
     return;
 
   gfx::Vector2dF scroll = top_controls_manager_->Animate(time);