Revert of Client side display item cache flag

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

 // Copyright 2015 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 DisplayItemClient_h
 #define DisplayItemClient_h
 
 #include "platform/PlatformExport.h"
 #include "platform/geometry/LayoutRect.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-// Holds a unique cache generation id of display items and paint controllers.
-//
-// A paint controller sets its cache generation to DisplayItemCacheGeneration::next()
-// at the end of each commitNewDisplayItems, and updates the cache generation of each
-// client with cached drawings by calling DisplayItemClient::setDisplayItemsCached().
-// A display item is treated as validly cached in a paint controller if its cache generation
-// matches the paint controller's cache generation.
-//
-// SPv1 only: If a display item is painted on multiple paint controllers, because cache
-// generations are unique, the client's cache generation matches the last paint controller
-// only. The client will be treated as invalid on other paint controllers regardless if
-// it's validly cached by these paint controllers. The situation is very rare (about 0.07%
-// clients were painted on multiple paint controllers) so the performance penalty is trivial.
-class PLATFORM_EXPORT DisplayItemCacheGeneration {
-    DISALLOW_NEW();
-public:
-    DisplayItemCacheGeneration() : m_value(kInvalidGeneration) { }
-
-    void invalidate() { m_value = kInvalidGeneration; }
-    static DisplayItemCacheGeneration next() { return DisplayItemCacheGeneration(s_nextGeneration++); }
-    bool matches(const DisplayItemCacheGeneration& other)
-    {
-        return m_value != kInvalidGeneration && other.m_value != kInvalidGeneration && m_value == other.m_value;
-    }
-
-private:
-    typedef uint32_t Generation;
-    DisplayItemCacheGeneration(Generation value) : m_value(value) { }
-
-    static const Generation kInvalidGeneration = 0;
-    static Generation s_nextGeneration;
-    Generation m_value;
-};
-
 // The interface for objects that can be associated with display items.
 // A DisplayItemClient object should live at least longer than the document cycle
 // in which its display items are created during painting.
 // After the document cycle, a pointer/reference to DisplayItemClient should be
 // no longer dereferenced unless we can make sure the client is still valid.
 class PLATFORM_EXPORT DisplayItemClient {
 public:
 #if ENABLE(ASSERT)
     DisplayItemClient();
     virtual ~DisplayItemClient();
 #else
     virtual ~DisplayItemClient() { }
 #endif
 
     virtual String debugName() const = 0;
 
     // The visual rect of this DisplayItemClient, in object space of the object that owns the GraphicsLayer, i.e.
     // offset by offsetFromLayoutObjectWithSubpixelAccumulation().
     virtual LayoutRect visualRect() const = 0;
 
-    virtual bool displayItemsAreCached(DisplayItemCacheGeneration) const = 0;
-    virtual void setDisplayItemsCached(DisplayItemCacheGeneration) const = 0;
-    virtual void setDisplayItemsUncached() const = 0;
-
 #if ENABLE(ASSERT)
     // Tests if a DisplayItemClient object has been created and has not been deleted yet.
     static bool isAlive(const DisplayItemClient&);
 #endif
-
-protected:
 };
 
-#define DISPLAY_ITEM_CACHE_STATUS_IMPLEMENTATION \
-    bool displayItemsAreCached(DisplayItemCacheGeneration cacheGeneration) const final { return m_cacheGeneration.matches(cacheGeneration); } \
-    void setDisplayItemsCached(DisplayItemCacheGeneration cacheGeneration) const final { m_cacheGeneration = cacheGeneration; } \
-    void setDisplayItemsUncached() const final { m_cacheGeneration.invalidate(); } \
-    mutable DisplayItemCacheGeneration m_cacheGeneration;
-
-#define DISPLAY_ITEM_CACHE_STATUS_UNCACHEABLE_IMPLEMENTATION \
-    bool displayItemsAreCached(DisplayItemCacheGeneration) const final { return false; } \
-    void setDisplayItemsCached(DisplayItemCacheGeneration) const final { } \
-    void setDisplayItemsUncached() const final { }
-
 inline bool operator==(const DisplayItemClient& client1, const DisplayItemClient& client2) { return &client1 == &client2; }
 inline bool operator!=(const DisplayItemClient& client1, const DisplayItemClient& client2) { return &client1 != &client2; }
 
 } // namespace blink
 
 #endif // DisplayItemClient_h