diff -r 000000000000 -r 6474c204b198 layout/base/nsArenaMemoryStats.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/base/nsArenaMemoryStats.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsArenaMemoryStats_h
+#define nsArenaMemoryStats_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/PodOperations.h"
+
+class nsTabSizes {
+public:
+  enum Kind {
+      DOM,        // DOM stuff.
+      Style,      // Style stuff.
+      Other       // Everything else.
+  };
+
+  nsTabSizes() { mozilla::PodZero(this); }
+
+  void add(Kind kind, size_t n)
+  {
+    switch (kind) {
+      case DOM:   mDom   += n; break;
+      case Style: mStyle += n; break;
+      case Other: mOther += n; break;
+      default:    MOZ_CRASH("bad nsTabSizes kind");
+    }
+  }
+
+  size_t mDom;
+  size_t mStyle;
+  size_t mOther;
+};
+
+#define FRAME_ID_STAT_FIELD(classname) mArena##classname
+
+struct nsArenaMemoryStats {
+#define FOR_EACH_SIZE(macro) \
+  macro(Other, mLineBoxes) \
+  macro(Style, mRuleNodes) \
+  macro(Style, mStyleContexts) \
+  macro(Other, mOther)
+
+  nsArenaMemoryStats()
+    :
+      #define ZERO_SIZE(kind, mSize) mSize(0),
+      FOR_EACH_SIZE(ZERO_SIZE)
+      #undef ZERO_SIZE
+      #define FRAME_ID(classname) FRAME_ID_STAT_FIELD(classname)(),
+      #include "nsFrameIdList.h"
+      #undef FRAME_ID
+      dummy()
+  {}
+
+  void addToTabSizes(nsTabSizes *sizes) const
+  {
+    #define ADD_TO_TAB_SIZES(kind, mSize) sizes->add(nsTabSizes::kind, mSize);
+    FOR_EACH_SIZE(ADD_TO_TAB_SIZES)
+    #undef ADD_TO_TAB_SIZES
+    #define FRAME_ID(classname) \
+      sizes->add(nsTabSizes::Other, FRAME_ID_STAT_FIELD(classname));
+    #include "nsFrameIdList.h"
+    #undef FRAME_ID
+  }
+
+  #define DECL_SIZE(kind, mSize) size_t mSize;
+  FOR_EACH_SIZE(DECL_SIZE)
+  #undef DECL_SIZE
+  #define FRAME_ID(classname) size_t FRAME_ID_STAT_FIELD(classname);
+  #include "nsFrameIdList.h"
+  #undef FRAME_ID
+  int dummy;  // present just to absorb the trailing comma from FRAME_ID in the
+              // constructor
+
+#undef FOR_EACH_SIZE
+};
+
+#endif // nsArenaMemoryStats_h