Refactor Node::showTree*() functions.

third_party/WebKit/Source/core/dom/Node.h

Index: third_party/WebKit/Source/core/dom/Node.h
diff --git a/third_party/WebKit/Source/core/dom/Node.h b/third_party/WebKit/Source/core/dom/Node.h
index 245d3a40366c7bb130dd27c742b3824210f1121f..a628169cf2cb58173c46f584944a59d52aea84bb 100644
--- a/third_party/WebKit/Source/core/dom/Node.h
+++ b/third_party/WebKit/Source/core/dom/Node.h
@@ -570,12 +570,13 @@ public:
     String debugName() const;
 
 #ifndef NDEBUG
+    String toString() const;
     void showNode(const char* prefix = "") const;
-    void showTreeForThis() const;
-    void showTreeForThisInFlatTree() const;
+    String toTreeStringForThis() const;
+    String toFlatTreeStringForThis() const;
     void printNodePathTo(std::ostream&) const;
-    void showTreeAndMark(const Node* markedNode1, const char* markedLabel1, const Node* markedNode2 = nullptr, const char* markedLabel2 = nullptr) const;
-    void showTreeAndMarkInFlatTree(const Node* markedNode1, const char* markedLabel1, const Node* markedNode2 = nullptr, const char* markedLabel2 = nullptr) const;
+    String toMarkedTreeString(const Node* markedNode1, const char* markedLabel1, const Node* markedNode2 = nullptr, const char* markedLabel2 = nullptr) const;
+    String toMarkedFlatTreeString(const Node* markedNode1, const char* markedLabel1, const Node* markedNode2 = nullptr, const char* markedLabel2 = nullptr) const;
     void showTreeForThisAcrossFrame() const;
 #endif