Blink handle selection handle visibility

cc/trees/layer_tree_impl.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_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1913 matching lines @@
   bool update_lcd_text = false;
   if (!UpdateDrawProperties(update_lcd_text))
     return NULL;
   FindTouchEventLayerFunctor func = {screen_space_point};
   FindClosestMatchingLayerState state;
   FindClosestMatchingLayer(screen_space_point, layer_list_[0], func, &state);
   return state.closest_match;
 }
 
 void LayerTreeImpl::RegisterSelection(const LayerSelection& selection) {
+  selection_changed_ = selection_ != selection;

[aelias_OOO_until_Jul13, 2016/08/08 21:30:51]

This relies on RegisterSelection being called again on the next commit.  But,
there may be multiple draws between two commits, and only the first draw is
needed.  I think we should be mutating state at draw time.

The damage-tracking code clears viewport_damage_rect_ in
LayerTreeHostImpl::PrepareToDraw.  I suggest roughly imitating that pattern for
this.

[amaralp, 2016/10/14 00:53:06]

Done.

   selection_ = selection;
 }
 
+bool LayerTreeImpl::SelectionChanged() {
+  return selection_changed_;
+}
+
 static gfx::SelectionBound ComputeViewportSelectionBound(
     const LayerSelectionBound& layer_bound,
     LayerImpl* layer,
     float device_scale_factor) {
   gfx::SelectionBound viewport_bound;
   viewport_bound.set_type(layer_bound.type);
 
   if (!layer || layer_bound.type == gfx::SelectionBound::EMPTY)
     return viewport_bound;
 
@@ skipping 86 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks and replicas.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc