Reland of Check DisplayItemCient aliveness in cached subsequences

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/Assertions.h"
@@ skipping 46 matching lines @@
 // no longer dereferenced unless we can make sure the client is still valid.
 class PLATFORM_EXPORT DisplayItemClient {
 public:
 #if CHECK_DISPLAY_ITEM_CLIENT_ALIVENESS
     DisplayItemClient();
     virtual ~DisplayItemClient();
 
     // Tests if this DisplayItemClient object has been created and has not been deleted yet.
     bool isAlive() const;
     // Called when any DisplayItem of this DisplayItemClient is added into PaintController
-    // using PaintController::createAndAppend().
-    void beginShouldKeepAlive(const void* paintController) const;
+    // using PaintController::createAndAppend() or into a cached subsequence.
+    void beginShouldKeepAlive(const void* owner) const;
     // Clears all should-keep-alive DisplayItemClients of a PaintController. Called after
-    // PaintController commits new display items.
-    static void endShouldKeepAliveAllClients(const void* paintController);
+    // PaintController commits new display items or the subsequence owner is invalidated.
+    static void endShouldKeepAliveAllClients(const void* owner);
     static void endShouldKeepAliveAllClients();
+
+    // Called to clear should-keep-alive of DisplayItemClients in a subsequence if this
+    // object is a subsequence.
+#define ON_DISPLAY_ITEM_CLIENT_INVALIDATION() endShouldKeepAliveAllClients(this)
 #else
     virtual ~DisplayItemClient() { }
+#define ON_DISPLAY_ITEM_CLIENT_INVALIDATION()
 #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;
 };
 
 #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(); } \
+    void setDisplayItemsUncached() const final \
+    { \
+        m_cacheGeneration.invalidate(); \
+        ON_DISPLAY_ITEM_CLIENT_INVALIDATION(); \
+    } \
     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