Route selection bounds updates through the compositor

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 9932a33be03d59d47c6ea65ad437c8a46b4e76a6..cca1887b78c095bfc4def79a42de370d2c366b6c 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -119,6 +119,8 @@ void LayerTreeImpl::SetRootLayer(scoped_ptr<LayerImpl> layer) {
   outer_viewport_scroll_layer_ = NULL;
   page_scale_layer_ = NULL;
 
+  ClearSelection();
+
   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 }
 
@@ -178,6 +180,8 @@ scoped_ptr<LayerImpl> LayerTreeImpl::DetachLayerTree() {
   page_scale_layer_ = NULL;
   currently_scrolling_layer_ = NULL;
 
+  ClearSelection();
+
   render_surface_layer_list_.clear();
   set_needs_update_draw_properties();
   return root_layer_.Pass();
@@ -209,6 +213,13 @@ void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
   } else {
     target_tree->ClearViewportLayers();
   }
+
+  target_tree->RegisterSelection(
+      start_selection_layer_ ? start_selection_layer_->id() : 0,
+      start_selection_handle_,
+      end_selection_layer_ ? end_selection_layer_->id() : 0,
+      end_selection_handle_);
+
   // This should match the property synchronization in
   // LayerTreeHost::finishCommitOnImplThread().
   target_tree->set_source_frame_number(source_frame_number());
@@ -1017,6 +1028,10 @@ void LayerTreeImpl::ReleaseResourcesRecursive(LayerImpl* current) {
     ReleaseResourcesRecursive(current->children()[i]);
 }
 
+void LayerTreeImpl::ClearSelection() {
+  RegisterSelection(0, SelectionHandle(), 0, SelectionHandle());
+}
+
 template <typename LayerType>
 static inline bool LayerClipsSubtree(LayerType* layer) {
   return layer->masks_to_bounds() || layer->mask_layer();
@@ -1097,8 +1112,8 @@ static bool PointHitsRegion(const gfx::PointF& screen_space_point,
 
 static bool PointIsClippedBySurfaceOrClipRect(
     const gfx::PointF& screen_space_point,
-    LayerImpl* layer) {
-  LayerImpl* current_layer = layer;
+    const LayerImpl* layer) {
+  const LayerImpl* current_layer = layer;
 
   // Walk up the layer tree and hit-test any render_surfaces and any layer
   // clip rects that are active.
@@ -1114,7 +1129,7 @@ static bool PointIsClippedBySurfaceOrClipRect(
     // Note that drawable content rects are actually in target surface space, so
     // the transform we have to provide is the target surface's
     // screen_space_transform.
-    LayerImpl* render_target = current_layer->render_target();
+    const LayerImpl* render_target = current_layer->render_target();
     if (LayerClipsSubtree(current_layer) &&
         !PointHitsRect(
             screen_space_point,
@@ -1131,7 +1146,7 @@ static bool PointIsClippedBySurfaceOrClipRect(
   return false;
 }
 
-static bool PointHitsLayer(LayerImpl* layer,
+static bool PointHitsLayer(const LayerImpl* layer,
                            const gfx::PointF& screen_space_point,
                            float* distance_to_intersection) {
   gfx::RectF content_rect(layer->content_bounds());
@@ -1275,4 +1290,59 @@ LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
   return data_for_recursion.closest_match;
 }
 
+void LayerTreeImpl::RegisterSelection(int start_layer_id,
+                                      const SelectionHandle& start_handle,
+                                      int end_layer_id,
+                                      const SelectionHandle& end_handle) {
+  start_selection_layer_ = start_layer_id ? LayerById(start_layer_id) : NULL;
+  end_selection_layer_ = end_layer_id ? LayerById(end_layer_id) : NULL;
+  start_selection_handle_ = start_handle;
+  end_selection_handle_ = end_handle;
+}
+
+static SelectionHandle ComputeSelectionVisibility(const SelectionHandle& handle,
+                                                  const LayerImpl* layer,
+                                                  float device_scale_factor) {
+  if (!layer || handle.type == SelectionHandle::NONE ||
+      handle.type == SelectionHandle::IGNORED)
+    return handle;
+
+  SelectionHandle result = handle;
+
+  gfx::QuadF layer_scaled_quad(gfx::ScaleRect(
+      handle.bounds, layer->contents_scale_x(), layer->contents_scale_y()));
+  bool handle_clipped = false;
+  gfx::QuadF screen_quad = MathUtil::ProjectQuad(
+      layer->screen_space_transform(), layer_scaled_quad, &handle_clipped);
+
+  float distance_to_intersection = 0.f;
+  result.visible =
+      !handle_clipped &&
+      PointHitsLayer(layer, screen_quad.p4(), &distance_to_intersection);
+
+  screen_quad.Scale(1.f / device_scale_factor);
+  result.bounds = screen_quad.BoundingBox();
+
+  return result;
+}
+
+void LayerTreeImpl::GetViewportSelection(SelectionHandle* start_handle,
+                                         SelectionHandle* end_handle) {
+  DCHECK(!needs_update_draw_properties_);
+  DCHECK(start_handle);
+  DCHECK(end_handle);
+
+  *start_handle = ComputeSelectionVisibility(
+      start_selection_handle_, start_selection_layer_, device_scale_factor());
+
+  if (start_handle->type == SelectionHandle::CENTER ||
+      start_handle->type == SelectionHandle::NONE ||
+      start_handle->type == SelectionHandle::IGNORED) {
+    *end_handle = *start_handle;
+  } else {
+    *end_handle = ComputeSelectionVisibility(
+        end_selection_handle_, end_selection_layer_, device_scale_factor());
+  }
+}
+
 }  // namespace cc