Don't cache subsequence whose layer is not fully contained by repaint rect

Source/platform/graphics/paint/SubsequenceRecorder.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 SubsequenceRecorder_h
 #define SubsequenceRecorder_h
 
 #include "platform/graphics/paint/DisplayItemClient.h"
 
 namespace blink {
 
 class DisplayItemList;
 class GraphicsContext;
 
 // SubsequenceRecorder records BeginSubsequenceDisplayItem and EndSubsequenceDisplayItem
 // sentinels at either end of a continguous sequence of DisplayItems, and supports
 // caching via a CachedDisplayItem with the CachedSubsequence DisplayItem type.
 //
 // Also note that useCachedSubsequenceIfPossible is not sufficient to determine whether a
 // CachedSubsequence can be used. In particular, the client is responsible for checking that
 // none of the DisplayItemClients that contribute to the subsequence have been invalidated.
 //
 class PLATFORM_EXPORT SubsequenceRecorder {
 public:
     static bool useCachedSubsequenceIfPossible(GraphicsContext&, const DisplayItemClientWrapper&);
 
     SubsequenceRecorder(GraphicsContext&, const DisplayItemClientWrapper&);
     ~SubsequenceRecorder();
 
+    void setUncacheable();
+
 private:
     DisplayItemList* m_displayItemList;
     DisplayItemClientWrapper m_client;
+    size_t m_beginSubsequenceIndex;
 };
 
 } // namespace blink
 
 #endif // SubsequenceRecorder_h