Make DisplayItemClient an interface

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

 // Copyright 2014 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 DisplayItem_h
 #define DisplayItem_h
 
 #include "platform/PlatformExport.h"
 #include "platform/graphics/ContiguousContainer.h"
 #include "platform/graphics/paint/DisplayItemClient.h"
@@ skipping 174 matching lines @@
     static_assert(TableCollapsedBorderBase >= TableCollapsedBorderUnalignedBase, "TableCollapsedBorder types overlap with other types");
     static_assert((TableCollapsedBorderBase & 0xf) == 0, "The lowest 4 bits of TableCollapsedBorderBase should be zero");
     // Bits or'ed onto TableCollapsedBorderBase to generate a real table collapsed border type.
     enum TableCollapsedBorderSides {
         TableCollapsedBorderTop = 1 << 0,
         TableCollapsedBorderRight = 1 << 1,
         TableCollapsedBorderBottom = 1 << 2,
         TableCollapsedBorderLeft = 1 << 3,
     };
 
-    DisplayItem(const DisplayItemClientWrapper& client, Type type, size_t derivedSize)
-        : m_client(client.displayItemClient())
+    DisplayItem(const DisplayItemClient& client, Type type, size_t derivedSize)
+        : m_client(&client)
         , m_scope(0)
         , m_type(type)
         , m_derivedSize(derivedSize)
         , m_skippedCache(false)
 #ifndef NDEBUG
         , m_clientDebugString(client.debugName())
 #endif
     {
         // derivedSize must fit in m_derivedSize.
         // If it doesn't, enlarge m_derivedSize and fix this assert.
         ASSERT_WITH_SECURITY_IMPLICATION(derivedSize < (1 << 8));
         ASSERT_WITH_SECURITY_IMPLICATION(derivedSize >= sizeof(*this));
     }
 
     virtual ~DisplayItem() { }
 
     // Ids are for matching new DisplayItems with existing DisplayItems.
     struct Id {
         STACK_ALLOCATED();
-        Id(const DisplayItemClient client, const Type type, const unsigned scope)
+        Id(const DisplayItemClient& client, const Type type, const unsigned scope)
             : client(client)
             , type(type)
             , scope(scope) { }
 
         bool matches(const DisplayItem& item) const
         {
             // We should always convert to non-cached types before matching.
             ASSERT(!isCachedType(item.m_type));
             ASSERT(!isCachedType(type));
-            return client == item.m_client
+            return &client == item.m_client
                 && type == item.m_type
                 && scope == item.m_scope;
         }
 
-        const DisplayItemClient client;
+        const DisplayItemClient& client;
         const Type type;
         const unsigned scope;
     };
 
     // Convert cached type to non-cached type (e.g., Type::CachedSVGImage -> Type::SVGImage).
     static Type nonCachedType(Type type)
     {
         if (isCachedDrawingType(type))
             return cachedDrawingTypeToDrawingType(type);
         if (type == CachedSubsequence)
             return Subsequence;
         return type;
     }
 
     // Return the Id with cached type converted to non-cached type.
     Id nonCachedId() const
     {
-        return Id(m_client, nonCachedType(m_type), m_scope);
+        return Id(*m_client, nonCachedType(m_type), m_scope);
     }
 
     virtual void replay(GraphicsContext&) const { }
 
-    DisplayItemClient client() const { return m_client; }
+    const DisplayItemClient& client() const { ASSERT(m_client); return *m_client; }
     Type type() const { return m_type; }
 
     void setScope(unsigned scope) { m_scope = scope; }
     unsigned scope() { return m_scope; }
 
     // Size of this object in memory, used to move it with memcpy.
     // This is not sizeof(*this), because it needs to account for the size of
     // the derived class (i.e. runtime type). Derived classes are expected to
     // supply this to the DisplayItem constructor.
     size_t derivedSize() const { return m_derivedSize; }
@@ skipping 73 matching lines @@
             && m_skippedCache == other.m_skippedCache;
     }
 #endif
 
     virtual bool drawsContent() const { return false; }
 
     bool isValid() const { return m_client; }
 
 #ifndef NDEBUG
     static WTF::String typeAsDebugString(DisplayItem::Type);
-    const WTF::String& clientDebugString() const { return m_clientDebugString; }
+    const WTF::String clientDebugString() const { return m_clientDebugString; }
     void setClientDebugString(const WTF::String& s) { m_clientDebugString = s; }
     WTF::String asDebugString() const;
     virtual void dumpPropertiesAsDebugString(WTF::StringBuilder&) const;
 #endif
 
 private:
     // The default DisplayItem constructor is only used by
     // ContiguousContainer::appendByMoving where an invalid DisplaItem is
     // constructed at the source location.
     template <typename T, unsigned alignment> friend class ContiguousContainer;
 
     DisplayItem()
         : m_client(nullptr)
         , m_scope(0)
         , m_type(UninitializedType)
         , m_derivedSize(sizeof(*this))
         , m_skippedCache(false)
     { }
 
-    const DisplayItemClient m_client;
+    const DisplayItemClient* m_client;
     unsigned m_scope;
     static_assert(TypeLast < (1 << 16), "DisplayItem::Type should fit in 16 bits");
     const Type m_type : 16;
     const unsigned m_derivedSize : 8; // size of the actual derived class
     unsigned m_skippedCache : 1;
 
 #ifndef NDEBUG
     WTF::String m_clientDebugString;
 #endif
 };
 
 class PLATFORM_EXPORT PairedBeginDisplayItem : public DisplayItem {
 protected:
-    PairedBeginDisplayItem(const DisplayItemClientWrapper& client, Type type, size_t derivedSize) : DisplayItem(client, type, derivedSize) { }
+    PairedBeginDisplayItem(const DisplayItemClient& client, Type type, size_t derivedSize) : DisplayItem(client, type, derivedSize) { }
 
 private:
     bool isBegin() const final { return true; }
 };
 
 class PLATFORM_EXPORT PairedEndDisplayItem : public DisplayItem {
 protected:
-    PairedEndDisplayItem(const DisplayItemClientWrapper& client, Type type, size_t derivedSize) : DisplayItem(client, type, derivedSize) { }
+    PairedEndDisplayItem(const DisplayItemClient& client, Type type, size_t derivedSize) : DisplayItem(client, type, derivedSize) { }
 
 #if ENABLE(ASSERT)
     bool isEndAndPairedWith(DisplayItem::Type otherType) const override = 0;
 #endif
 
 private:
     bool isEnd() const final { return true; }
 };
 
 } // namespace blink
 
 #endif // DisplayItem_h