cc: Refactor how picture layers are exposed to the tile manager.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 94d2864c696535575997ee2d32c898b0d00816eb..1d8598a47cc5debc65192b4099c3258bb1893be5 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1236,6 +1236,10 @@ void LayerTreeHostImpl::DidInitializeVisibleTile() {
     client_->DidInitializeVisibleTileOnImplThread();
 }
 
+const std::vector<PictureLayerImpl*>& LayerTreeHostImpl::GetPictureLayers() {
+  return picture_layers_;
+}
+
 void LayerTreeHostImpl::NotifyReadyToActivate() {
   client_->NotifyReadyToActivate();
 }
@@ -3135,4 +3139,17 @@ void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfSetNeedsRedraw() {
     (*it)->OnSetNeedsRedrawOnImpl();
 }
 
+void LayerTreeHostImpl::RegisterPictureLayerImpl(PictureLayerImpl* layer) {
+  DCHECK(std::find(picture_layers_.begin(), picture_layers_.end(), layer) ==
+         picture_layers_.end());
+  picture_layers_.push_back(layer);
+}
+
+void LayerTreeHostImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
+  std::vector<PictureLayerImpl*>::iterator it =
+      std::find(picture_layers_.begin(), picture_layers_.end(), layer);
+  DCHECK(it != picture_layers_.end());
+  picture_layers_.erase(it);
+}
+
 }  // namespace cc