Add debugging output for visual rects in PaintController.

third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
index e478f8a76bf0250f84190cb79094c9567d8b1a19..46b1bdec84ab8531d01d1bf43fc4bfee754bbd95 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
@@ -492,7 +492,7 @@ void PaintController::checkCachedDisplayItemIsUnchanged(const char* messagePrefi
 
 #ifndef NDEBUG
 
-WTF::String PaintController::displayItemListAsDebugString(const DisplayItemList& list) const
+String PaintController::displayItemListAsDebugString(const DisplayItemList& list) const
 {
     StringBuilder stringBuilder;
     size_t i = 0;
@@ -506,6 +506,10 @@ WTF::String PaintController::displayItemListAsDebugString(const DisplayItemList&
             stringBuilder.append(", cacheIsValid: ");
             stringBuilder.append(clientCacheIsValid(displayItem.client()) ? "true" : "false");
         }
+        IntRect visualRect = list.visualRect(i);

[wkorman, 2016/07/01 19:04:06]

I think that this can/will lead to a failed DCHECK assert with i >= visual rect
vector size, in this debug block:

https://cs.chromium.org/chromium/src/third_party/WebKit/Source/platform/graph...

+        stringBuilder.append(String::format(", visualRect: [%d,%d %dx%d]",
+            visualRect.x(), visualRect.y(),
+            visualRect.width(), visualRect.height()));
         stringBuilder.append('}');
     }
     return stringBuilder.toString();