Attribute Stuff to Frames with FrameBlamer

third_party/WebKit/Source/core/frame/LocalFrame.h

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999-2001 Lars Knoll <knoll@kde.org>
  *                     1999-2001 Antti Koivisto <koivisto@kde.org>
  *                     2000-2001 Simon Hausmann <hausmann@kde.org>
  *                     2000-2001 Dirk Mueller <mueller@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
@@ skipping 296 matching lines @@
     WTF_MAKE_NONCOPYABLE(FrameNavigationDisabler);
     STACK_ALLOCATED();
 public:
     explicit FrameNavigationDisabler(LocalFrame&);
     ~FrameNavigationDisabler();
 
 private:
     Member<LocalFrame> m_frame;
 };
 
+// A helper class for attributing cost inside a scope to a LocalFrame, with
+// output written to the trace log. The class is irrelevant to the core logic
+// of LocalFrame.  Sample usage:
+//
+// void foo(LocalFrame* frame)
+// {
+//     ScopedFrameBlamer frameBlamer(frame);
+//     TRACE_EVENT0("blink", "foo");
+//     // Do some real work...
+// }
+//
+// In Trace Viewer, we can find the cost of slice |foo| attributed to |frame|.
+// Design doc: https://docs.google.com/document/d/15BB-suCb9j-nFt55yCFJBJCGzLg2qUm3WaSOPb8APtI/edit?usp=sharing
+class ScopedFrameBlamer {
+    WTF_MAKE_NONCOPYABLE(ScopedFrameBlamer);
+    STACK_ALLOCATED();
+public:
+    explicit ScopedFrameBlamer(LocalFrame*);
+    ~ScopedFrameBlamer();
+
+private:
+    Member<LocalFrame> m_frame;
+};
+
 } // namespace blink
 
 #endif // LocalFrame_h