Manage registering composited elements in PaintArtifactCompositor.

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp

Index: third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
index 612385a0f360279353a80562b430d51db769a035..bcc1702700290a9fffc787e6c0787b23f4c03aca 100644
--- a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
+++ b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
@@ -9,6 +9,7 @@
 #include "cc/layers/picture_layer.h"
 #include "cc/paint/display_item_list.h"
 #include "cc/trees/layer_tree_host.h"
+#include "cc/trees/mutator_host_client.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/compositing/PaintChunksToCcLayer.h"
@@ -656,6 +657,18 @@ void PaintArtifactCompositor::Update(
     }
 
     root_layer_->AddChild(layer);
+    if (auto previous_host = layer->layer_tree_host()) {
+      previous_host->UnregisterElement(element_id, cc::ElementListType::ACTIVE,
+                                       layer.get());
+    }
+    if (element_id) {
+      auto host = root_layer_->layer_tree_host();
+      host->RegisterElement(element_id, cc::ElementListType::ACTIVE,
+                            layer.get());
+      if (host->mutator_host()->HasAnyAnimation(element_id))

[wkorman, 2017/05/17 20:07:50]

Believe we actually don't need to do this in SPv2, removed in latest patch set.
We appear to SetNeedsCommit on the LTH every time Update is called.

+        host->SetNeedsCommit();
+    }
+
     layer->set_property_tree_sequence_number(g_s_property_tree_sequence_number);
     layer->SetTransformTreeIndex(transform_id);
     layer->SetClipTreeIndex(clip_id);