cc: Make visible rect computation aware of pixel-moving filters

cc/trees/clip_node.h

Index: cc/trees/clip_node.h
diff --git a/cc/trees/clip_node.h b/cc/trees/clip_node.h
index fe315d460528f20b3e10a66d55842edbe5dffe93..6d165b971a9836bf9f8b4d5aed344a97a1e8b3e4 100644
--- a/cc/trees/clip_node.h
+++ b/cc/trees/clip_node.h
@@ -5,7 +5,10 @@
 #ifndef CC_TREES_CLIP_NODE_H_
 #define CC_TREES_CLIP_NODE_H_
 
+#include <memory>
+
 #include "cc/base/cc_export.h"
+#include "cc/trees/clip_expander.h"
 #include "ui/gfx/geometry/rect_f.h"
 
 namespace base {
@@ -24,6 +27,10 @@ struct CC_EXPORT ClipNode {
   ClipNode();
   ClipNode(const ClipNode& other);
 
+  ClipNode& operator=(const ClipNode& other);
+
+  ~ClipNode();
+
   int id;
   int parent_id;
   int owner_id;
@@ -34,7 +41,15 @@ struct CC_EXPORT ClipNode {
     NONE,
 
     // The node contributes a new clip (that is, |clip| needs to be applied).
-    APPLIES_LOCAL_CLIP
+    APPLIES_LOCAL_CLIP,
+
+    // This node represents a space expansion. When computing visible rects,
+    // the accumulated clip inherited by this node gets expanded. Similarly,
+    // when mapping a rect in descendant space to the rect in ancestor space
+    // that depends on the descendant rect's contents, this node expands the
+    // descendant rect. This is used for effects like pixel-moving filters,
+    // where clipped-out content can affect visible output.
+    EXPANDS_CLIP
   };
 
   ClipType clip_type;
@@ -43,6 +58,9 @@ struct CC_EXPORT ClipNode {
   // transform node.
   gfx::RectF clip;
 
+  // For nodes that expand, this represents the amount of expansion.
+  std::unique_ptr<ClipExpander> clip_expander;
+
   // Clip nodes are used for two reasons. First, they are used for determining
   // which parts of each layer are visible. Second, they are used for
   // determining whether a clip needs to be applied when drawing a layer, and if