Allows fullscreen to be triggered with the key events used for scrolling.

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 913ca1b1fc8131557fbeaffa9cf095759a1f9dc0..d033cbb2b4535f8ab1bbc4c19c306cc6d710b52f 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -1048,6 +1048,18 @@ void LayerTreeHost::UpdateTopControlsState(TopControlsState constraints,
                  animate));
 }
 
+void LayerTreeHost::UpdateTopControlsStatePreservingConstraints(
+    bool show) {
+  if (!settings_.calculate_top_controls_position)
+    return;
+  proxy_->ImplThread()->PostTask(
+      base::Bind(
+          &TopControlsManager::UpdateTopControlsStatePreservingConstraints,
+          top_controls_manager_weak_ptr_,
+          show ? cc::SHOWN : cc::HIDDEN,
+          true));
+}
+
 bool LayerTreeHost::BlocksPendingCommit() const {
   if (!root_layer_.get())
     return false;