Don't access DisplayItemClient::VisualRect() for cached display items.

third_party/WebKit/Source/platform/graphics/paint/DisplayItem.h

Index: third_party/WebKit/Source/platform/graphics/paint/DisplayItem.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/DisplayItem.h b/third_party/WebKit/Source/platform/graphics/paint/DisplayItem.h
index d5f344e605f4b55ad17dfdc5ccdad84f39636a49..76930d7c903e1b9020bfe681b9fea89736911a9c 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/DisplayItem.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/DisplayItem.h
@@ -20,7 +20,7 @@
 namespace blink {
 
 class GraphicsContext;
-class IntRect;
+class LayoutSize;

[pdr., 2017/05/19 17:11:36]

Curious: why a LayoutSize instead of an IntSize or a FloatSize?

[Xianzhu, 2017/05/19 18:06:33]

This is for the "const LayoutSize& visual_rect_offset" parameter of
AppendToWebDisplayItemList(). Previously the parameter was "const IntRect&
visual_rect".

The offset is from
GraphicsLayer::OffsetFromLayoutObjectWithSubpixelAccumulation() which is a
LayoutSize.

Added comments about the parameter.

 class WebDisplayItemList;
 
 class PLATFORM_EXPORT DisplayItem {
@@ -199,6 +199,7 @@ class PLATFORM_EXPORT DisplayItem {
 
   DisplayItem(const DisplayItemClient& client, Type type, size_t derived_size)
       : client_(&client),
+        visual_rect_(client.VisualRect()),
         type_(type),
         derived_size_(derived_size),
         skipped_cache_(false)
@@ -233,6 +234,9 @@ class PLATFORM_EXPORT DisplayItem {
     DCHECK(client_);
     return *client_;
   }
+
+  const LayoutRect& VisualRect() const { return visual_rect_; }

[pdr., 2017/05/19 17:11:36]

Can you add a comment here about what space this rect is in?

[Xianzhu, 2017/05/19 18:06:33]

Done.

+
   Type GetType() const { return type_; }
 
   // Size of this object in memory, used to move it with memcpy.
@@ -246,9 +250,7 @@ class PLATFORM_EXPORT DisplayItem {
   void SetSkippedCache() { skipped_cache_ = true; }
   bool SkippedCache() const { return skipped_cache_; }
 
-  // TODO(wkorman): Only DrawingDisplayItem needs the visual rect argument.
-  // Consider refactoring class hierarchy to make this more explicit.
-  virtual void AppendToWebDisplayItemList(const IntRect&,
+  virtual void AppendToWebDisplayItemList(const LayoutSize&,
                                           WebDisplayItemList*) const {}
 
 // See comments of enum Type for usage of the following macros.
@@ -351,6 +353,7 @@ class PLATFORM_EXPORT DisplayItem {
   // constructed at the source location.
   template <typename T, unsigned alignment>
   friend class ContiguousContainer;
+  friend class DisplayItemList;
 
   DisplayItem()
       : client_(nullptr),
@@ -359,6 +362,8 @@ class PLATFORM_EXPORT DisplayItem {
         skipped_cache_(false) {}
 
   const DisplayItemClient* client_;
+  LayoutRect visual_rect_;
+
   static_assert(kTypeLast < (1 << 16),
                 "DisplayItem::Type should fit in 16 bits");
   const Type type_ : 16;