[SP] Always paint whole non-custom scrollbars

Source/platform/graphics/paint/DisplayItemList.cpp

 // 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.
 
 #include "config.h"
 #include "platform/graphics/paint/DisplayItemList.h"
 
 #include "platform/NotImplemented.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/TraceEvent.h"
@@ skipping 224 matching lines @@
             && m_currentDisplayItems[currentDisplayItemsIndex]
             && m_currentDisplayItems[currentDisplayItemsIndex]->idsEqual(*newDisplayItem, matchingType);
 
         if (newDisplayItem->isCached()) {
             ASSERT(!RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled());
             ASSERT(clientCacheIsValid(newDisplayItem->client()));
             if (isSynchronized) {
                 updatedList.append(m_currentDisplayItems[currentDisplayItemsIndex].release());
             } else {
                 size_t foundIndex = findOutOfOrderCachedItem(currentDisplayItemsIndex, *newDisplayItem, matchingType, displayItemIndicesByClient);
-                if (foundIndex != kNotFound) {
-                    isSynchronized = (foundIndex == currentDisplayItemsIndex);
-                    updatedList.append(m_currentDisplayItems[foundIndex].release());
-                }
-                // else: do nothing because previously the client generated a empty picture which is not stored in the cache.

[chrishtr, 2015/06/03 21:19:21]

The behavior this comment refers to was removed earlier?

[Xianzhu, 2015/06/03 21:32:56]

Yes. I should have changed the above when I added back dummy display items.

+                ASSERT(foundIndex != kNotFound);
+                isSynchronized = (foundIndex == currentDisplayItemsIndex);
+                updatedList.append(m_currentDisplayItems[foundIndex].release());
             }
         } else {
 #if ENABLE(ASSERT)
             if (RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled())
                 checkCachedDisplayItemIsUnchanged(*newDisplayItem, displayItemIndicesByClient);
             else
                 ASSERT(!newDisplayItem->isDrawing() || !clientCacheIsValid(newDisplayItem->client()));
 #endif // ENABLE(ASSERT)
             updatedList.append(newDisplayItem.release());
         }
@@ skipping 175 matching lines @@
 
 void DisplayItemList::replay(GraphicsContext& context) const
 {
     TRACE_EVENT0("blink,benchmark", "DisplayItemList::replay");
     ASSERT(m_newDisplayItems.isEmpty());
     for (auto& displayItem : m_currentDisplayItems)
         displayItem->replay(context);
 }
 
 } // namespace blink