Update from https://crrev.com/316786

cc/trees/layer_tree_host.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.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 101 matching lines @@
       inside_begin_main_frame_(false),
       needs_full_tree_sync_(true),
       client_(client),
       source_frame_number_(0),
       rendering_stats_instrumentation_(RenderingStatsInstrumentation::Create()),
       output_surface_lost_(true),
       settings_(settings),
       debug_state_(settings.initial_debug_state),
       top_controls_shrink_blink_size_(false),
       top_controls_height_(0.f),
-      top_controls_content_offset_(0.f),
+      top_controls_shown_ratio_(0.f),
       device_scale_factor_(1.f),
       visible_(true),
       page_scale_factor_(1.f),
       min_page_scale_factor_(1.f),
       max_page_scale_factor_(1.f),
       has_gpu_rasterization_trigger_(false),
       content_is_suitable_for_gpu_rasterization_(true),
       gpu_rasterization_histogram_recorded_(false),
       background_color_(SK_ColorWHITE),
       has_transparent_background_(false),
@@ skipping 195 matching lines @@
   sync_tree->RegisterSelection(selection_start_, selection_end_);
 
   sync_tree->PushPageScaleFromMainThread(
       page_scale_factor_, min_page_scale_factor_, max_page_scale_factor_);
   sync_tree->elastic_overscroll()->PushFromMainThread(elastic_overscroll_);
   if (sync_tree->IsActiveTree())
     sync_tree->elastic_overscroll()->PushPendingToActive();
 
   sync_tree->PassSwapPromises(&swap_promise_list_);
 
-  // Track the change in top controls height to offset the top_controls_delta
-  // properly.  This is so that the top controls offset will be maintained
-  // across height changes.
-  float top_controls_height_delta =
-      sync_tree->top_controls_height() - top_controls_height_;
-
   sync_tree->set_top_controls_shrink_blink_size(
       top_controls_shrink_blink_size_);
   sync_tree->set_top_controls_height(top_controls_height_);
-  sync_tree->set_top_controls_content_offset(top_controls_content_offset_);
-  sync_tree->set_top_controls_delta(sync_tree->top_controls_delta() -
-                                    sync_tree->sent_top_controls_delta() -
-                                    top_controls_height_delta);
-  sync_tree->set_sent_top_controls_delta(0.f);
+  sync_tree->PushTopControlsFromMainThread(top_controls_shown_ratio_);
 
   host_impl->SetUseGpuRasterization(UseGpuRasterization());
   host_impl->set_gpu_rasterization_status(GetGpuRasterizationStatus());
   RecordGpuRasterizationHistogram();
 
   host_impl->SetViewportSize(device_viewport_size_);
   host_impl->SetDeviceScaleFactor(device_scale_factor_);
   host_impl->SetDebugState(debug_state_);
   if (pending_page_scale_animation_) {
     sync_tree->SetPendingPageScaleAnimation(
@@ skipping 322 matching lines @@
 }
 
 void LayerTreeHost::SetTopControlsHeight(float height) {
   if (top_controls_height_ == height)
     return;
 
   top_controls_height_ = height;
   SetNeedsCommit();
 }
 
-void LayerTreeHost::SetTopControlsContentOffset(float offset) {
-  if (top_controls_content_offset_ == offset)
+void LayerTreeHost::SetTopControlsShownRatio(float ratio) {
+  if (top_controls_shown_ratio_ == ratio)
     return;
 
-  top_controls_content_offset_ = offset;
+  top_controls_shown_ratio_ = ratio;
   SetNeedsCommit();
 }
 
 void LayerTreeHost::ApplyPageScaleDeltaFromImplSide(float page_scale_delta) {
   DCHECK(CommitRequested());
   page_scale_factor_ *= page_scale_delta;
 }
 
 void LayerTreeHost::SetPageScaleFactorAndLimits(float page_scale_factor,
                                                 float min_page_scale_factor,
@@ skipping 513 matching lines @@
   // Top controls are only used in threaded mode.
   proxy_->ImplThreadTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&TopControlsManager::UpdateTopControlsState,
                  top_controls_manager_weak_ptr_,
                  constraints,
                  current,
                  animate));
 }
 
-void LayerTreeHost::AsValueInto(base::debug::TracedValue* state) const {
+void LayerTreeHost::AsValueInto(base::trace_event::TracedValue* state) const {
   state->BeginDictionary("proxy");
   proxy_->AsValueInto(state);
   state->EndDictionary();
 }
 
 void LayerTreeHost::AnimateLayers(base::TimeTicks monotonic_time) {
   if (!settings_.accelerated_animation_enabled ||
       animation_registrar_->active_animation_controllers().empty())
     return;
 
@@ skipping 137 matching lines @@
     bool children_need_begin_frames) const {
   proxy_->SetChildrenNeedBeginFrames(children_need_begin_frames);
 }
 
 void LayerTreeHost::SendBeginFramesToChildren(
     const BeginFrameArgs& args) const {
   client_->SendBeginFramesToChildren(args);
 }
 
 }  // namespace cc