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

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index fc99e9e92229c86a9cdddb3ce16ed3cc11387ed8..bf8b1458c76894ce232b0301937f032b998d6035 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -106,7 +106,7 @@ LayerTreeHost::LayerTreeHost(LayerTreeHostClient* client,
       num_failed_recreate_attempts_(0),
       settings_(settings),
       debug_state_(settings.initial_debug_state),
-      top_controls_layout_height_(0.f),
+      top_controls_content_offset_(0.f),
       device_scale_factor_(1.f),
       visible_(true),
       page_scale_factor_(1.f),
@@ -347,11 +347,16 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
 
   sync_tree->PassSwapPromises(&swap_promise_list_);
 
+  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());
+  sync_tree->set_sent_top_controls_delta(0.f);
+
   host_impl->SetUseGpuRasterization(UseGpuRasterization());
   RecordGpuRasterizationHistogram();
 
   host_impl->SetViewportSize(device_viewport_size_);
-  host_impl->SetTopControlsLayoutHeight(top_controls_layout_height_);
   host_impl->SetDeviceScaleFactor(device_scale_factor_);
   host_impl->SetDebugState(debug_state_);
   if (pending_page_scale_animation_) {
@@ -627,12 +632,11 @@ void LayerTreeHost::SetViewportSize(const gfx::Size& device_viewport_size) {
   SetNeedsCommit();
 }
 
-void LayerTreeHost::SetTopControlsLayoutHeight(
-    float top_controls_layout_height) {
-  if (top_controls_layout_height_ == top_controls_layout_height)
+void LayerTreeHost::SetTopControlsContentOffset(float offset) {
+  if (top_controls_content_offset_ == offset)
     return;
 
-  top_controls_layout_height_ = top_controls_layout_height;
+  top_controls_content_offset_ = offset;
   SetNeedsCommit();
 }
 
@@ -1072,7 +1076,9 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
   }
 
   if (!inner_viewport_scroll_delta.IsZero() ||
-      !outer_viewport_scroll_delta.IsZero() || info->page_scale_delta != 1.f) {
+      !outer_viewport_scroll_delta.IsZero() ||
+      info->page_scale_delta != 1.f ||
+      info->top_controls_content_offset != top_controls_content_offset_) {
     // SetScrollOffsetFromImplSide above could have destroyed the tree,
     // so re-get this layer before doing anything to it.
 
@@ -1081,6 +1087,10 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
     // value, then the layer can early out without needing a full commit.
     DCHECK(inner_viewport_scroll_layer_.get());  // We should always have this.
 
+    // TODO(bokan): Fold this call into the client_->ApplyScrollAndScale call
+    // below once single viewport pinch is removed.
+    client_->SetTopControlsContentOffset(info->top_controls_content_offset);
+
     inner_viewport_scroll_layer_->SetScrollOffsetFromImplSide(
         inner_viewport_scroll_layer_->scroll_offset() +
         inner_viewport_scroll_delta);