Emit dummy display item when recorded picture is empty

Source/platform/graphics/paint/DrawingRecorder.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/DrawingRecorder.h"
 
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/GraphicsLayer.h"
@@ skipping 46 matching lines @@
 
     if (m_canUseCachedDrawing) {
 #if ENABLE(ASSERT)
         RefPtr<const SkPicture> picture = m_context->endRecording();
         ASSERT(!picture || !picture->approximateOpCount());
 #endif
         displayItem = CachedDisplayItem::create(m_displayItemClient, m_displayItemType);
     } else {
         RefPtr<const SkPicture> picture = m_context->endRecording();
         if (!picture || !picture->approximateOpCount())
-            return;
-        displayItem = DrawingDisplayItem::create(m_displayItemClient, m_displayItemType, picture);
+            displayItem = DisplayItem::createDummy(m_displayItemClient, m_displayItemType);
+        else
+            displayItem = DrawingDisplayItem::create(m_displayItemClient, m_displayItemType, picture);
     }
 
 #ifndef NDEBUG
     displayItem->setClientDebugString(m_clientDebugString);
 #endif
 
     m_context->displayItemList()->add(displayItem.release());
 }
 
 #ifndef NDEBUG
 void DrawingRecorder::setClientDebugString(const WTF::String& clientDebugString)
 {
     m_clientDebugString = clientDebugString;
 }
 #endif
 
 } // namespace blink