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

cc/trees/clip_node.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #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 {
 namespace trace_event {
 class TracedValue;
 }  // namespace trace_event
 }  // namespace base
 
 namespace cc {
 
 struct CC_EXPORT ClipNode {
   ClipNode();
   ClipNode(const ClipNode& other);
 
+  ClipNode& operator=(const ClipNode& other);
+
+  ~ClipNode();
+
   // The node index of this node in the clip tree node vector.
   int id;
   // The node index of the parent node in the clip tree node vector.
   int parent_id;
   // The layer id of the layer that owns this node.
   int owning_layer_id;
 
   enum class ClipType {
     // The node doesn't contribute a new clip. It exists only for caching clips
     // or for resetting clipping state.
     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;
 
   // The clip rect that this node contributes, expressed in the space of its
   // 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
   // so, the rect that needs to be used. These can be different since not all
   // clips need to be applied directly to each layer. For example, a layer is
   // implicitly clipped by the bounds of its target render surface and by clips
   // applied to this surface. |combined_clip_in_target_space| is used for
   // computing visible rects, and |clip_in_target_space| is used for computing
   // clips applied at draw time. Both rects are expressed in the space of the
   // target transform node, and may include clips contributed by ancestors.
@@ skipping 25 matching lines @@
   bool resets_clip : 1;
 
   bool operator==(const ClipNode& other) const;
 
   void AsValueInto(base::trace_event::TracedValue* value) const;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_CLIP_NODE_H_