Emit dummy display item when recorded picture is empty

Source/platform/graphics/paint/DisplayItem.cpp

Index: Source/platform/graphics/paint/DisplayItem.cpp
diff --git a/Source/platform/graphics/paint/DisplayItem.cpp b/Source/platform/graphics/paint/DisplayItem.cpp
index cd1d1516b233c900aa2f58ff9ab27050fd9654fc..429fbe92972a230bb4c506aa2162489b292d7cb9 100644
--- a/Source/platform/graphics/paint/DisplayItem.cpp
+++ b/Source/platform/graphics/paint/DisplayItem.cpp
@@ -7,6 +7,25 @@
 
 namespace blink {
 
+namespace {

[pdr., 2014/12/12 18:39:04]

Does this need to be in a namespace block?

+
+class DummyDisplayItem : public DisplayItem {
+public:
+    DummyDisplayItem(DisplayItemClient client, Type type) : DisplayItem(client, type) { }
+
+private:
+    virtual void replay(GraphicsContext*) override final { }
+    virtual void appendToWebDisplayItemList(WebDisplayItemList*) const override final { }
+    virtual const char* name() const override final { return "Dummy"; }
+};
+
+} // namespace
+
+PassOwnPtr<DisplayItem> DisplayItem::createDummy(DisplayItemClient client, Type type)
+{
+    return adoptPtr(new DummyDisplayItem(client, type));
+}
+
 #ifndef NDEBUG
 
 WTF::String DisplayItem::typeAsDebugString(DisplayItem::Type type)
@@ -74,13 +93,14 @@ WTF::String DisplayItem::asDebugString() const
 
 void DisplayItem::dumpPropertiesAsDebugString(WTF::StringBuilder& stringBuilder) const
 {
+    stringBuilder.append("name: \"");
+    stringBuilder.append(name());
+    stringBuilder.append("\", ");
     if (!clientDebugString().isEmpty()) {
         stringBuilder.append(clientDebugString());
         stringBuilder.append(", ");
     }
     stringBuilder.append("type: \"");
-    if (isCached())

[pdr., 2014/12/12 18:39:04]

Any reason for removing this?

[Xianzhu, 2014/12/12 19:11:17]

Now the new "name" attribute can show the same information, so this becomes
redundant.

-        stringBuilder.append("Cached-");
     stringBuilder.append(typeAsDebugString(type()));
     stringBuilder.append('"');
 }