Cleanups of PaintController

third_party/WebKit/Source/platform/graphics/paint/PaintController.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 "platform/graphics/paint/PaintController.h"
 
 #include "platform/TraceEvent.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/paint/DrawingDisplayItem.h"
 #include "third_party/skia/include/core/SkPictureAnalyzer.h"
@@ skipping 719 matching lines @@
                 visualRect.x(), visualRect.y(),
                 visualRect.width(), visualRect.height()));
         }
         stringBuilder.append('}');
     }
     return stringBuilder.toString();
 }
 
 void PaintController::showDebugDataInternal(bool showPictures) const
 {
+    // In NDEBUG mode we call DisplayItemClient::debugName() in displayItemListAsDebugString() which can only be called
+    // when we are sure the client is still alive. It's not suitable for m_currentPaintArtifact.getDisplayItemList().
+#ifndef NDEBUG

[pdr., 2016/09/12 19:45:07]

I'd prefer if this function didn't work completely differently depending on
ndebug. Is there a way to check for liveness in displayItemListAsDebugString in
ndebug mode and still print the rest of the information? If not, could we just
delete the m_currentPaintArtifact part?

[Xianzhu, 2016/09/12 20:54:49]

We can't enable liveness checking in release build because it's expensive.
The m_currentPaintArtifact is important for debugging the merge algorithm.

In the new patch set, I changed PaintController::displayItemListAsDebugString()
instead of PaintController::showDebugDataInternal() to minimize the differences
between release and debug builds.

     WTFLogAlways("current display item list: [%s]\n", displayItemListAsDebugString(m_currentPaintArtifact.getDisplayItemList(), showPictures).utf8().data());
+#endif
     WTFLogAlways("new display item list: [%s]\n", displayItemListAsDebugString(m_newDisplayItemList, showPictures).utf8().data());
 }
 
 } // namespace blink