Reland of "Tracking reference filter mutation via SVGElementProxy"

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp

Index: third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
diff --git a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
index f7c2771743141f28f8d65ed237fec5339e22348b..9cf2cb0c58f2294695b0d661e3f211a7b66dd9f8 100644
--- a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
+++ b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.cpp
@@ -221,6 +221,7 @@ void CanvasRenderingContext2D::didSetSurfaceSize() {
 
 DEFINE_TRACE(CanvasRenderingContext2D) {
   visitor->trace(m_hitRegionManager);
+  visitor->trace(m_filterOperations);
   CanvasRenderingContext::trace(visitor);
   BaseRenderingContext2D::trace(visitor);
   SVGResourceClient::trace(visitor);
@@ -565,7 +566,28 @@ void CanvasRenderingContext2D::styleDidChange(const ComputedStyle* oldStyle,
   pruneLocalFontCache(0);
 }
 
-void CanvasRenderingContext2D::filterNeedsInvalidation() {
+TreeScope* CanvasRenderingContext2D::treeScope() {
+  return &canvas()->treeScope();
+}
+
+void CanvasRenderingContext2D::clearFilterReferences() {
+  m_filterOperations.removeClient(this);
+  m_filterOperations.clear();
+}
+
+void CanvasRenderingContext2D::updateFilterReferences(
+    const FilterOperations& filters) {
+  clearFilterReferences();
+  filters.addClient(this);
+  m_filterOperations = filters;
+}
+
+void CanvasRenderingContext2D::resourceContentChanged() {
+  resourceElementChanged();
+}
+
+void CanvasRenderingContext2D::resourceElementChanged() {
+  clearFilterReferences();
   state().clearResolvedFilter();
 }