Track reasons for |Node::SetNeedsStyleRecalc|

Source/core/dom/StyleChangeReason.h

Index: Source/core/dom/StyleChangeReason.h
diff --git a/Source/core/dom/StyleChangeReason.h b/Source/core/dom/StyleChangeReason.h
new file mode 100644
index 0000000000000000000000000000000000000000..46d354f95c5fb6d8ebdc3254eb585f0b6764fd7f
--- /dev/null
+++ b/Source/core/dom/StyleChangeReason.h
@@ -0,0 +1,62 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef StyleChangeReason_h
+#define StyleChangeReason_h
+
+#include "wtf/Assertions.h"
+
+namespace blink {
+
+// |StyleChangeReasonForTracing| is used to trace the reason a
+// |Node::setNeedsStyleRecalc| call was made to show it in DevTools or in
+// about:tracing.
+// |StyleChangeReasonForTracing| is strictly only for the tracing purpose as
+// described above. Blink logic must not depend on this value.
+namespace StyleChangeReasonForTracing {
+extern const char ActivePseudoClass[];
+extern const char ActiveStylesheetsUpdate[];
+extern const char Animation[];
+extern const char Attribute[];
+extern const char CellBorderPaddingChange[];
+extern const char Control[];
+extern const char ControlValue[];
+extern const char CustomElement[];
+extern const char DesignMode[];
+extern const char DisabledPseudoClass[];
+extern const char Drag[];
+extern const char EmptyPseudoClass[];
+extern const char FocusPseudoClass[];
+extern const char FontSizeChange[];
+extern const char Fonts[];
+extern const char FrameSet[];
+extern const char FullScreen[];
+extern const char HoverPseudoClass[];
+extern const char Inline[];
+extern const char Inspector[];
+extern const char InvalidPseudoClass[];
+extern const char Language[];
+extern const char LinkColorChange[];
+extern const char PlatformColorChange[];
+extern const char Plugin[];
+extern const char RequiredOptionalPseudoClass[];
+extern const char SVGContainerSizeChange[];
+extern const char SVGCursor[];
+extern const char SVGFilterLayerUpdate[];
+extern const char Selector[];
+extern const char Shadow[];
+extern const char SiblingSelector[];
+extern const char StyleInvalidator[];
+extern const char StyleSheetChange[];
+extern const char ViewportUnits[];
+extern const char VisitedLink[];
+extern const char VisuallyOrdered[];
+extern const char WritingModeChange[];
+extern const char Zoom[];
+};
+typedef const char StyleChangeReasonString[];
+
+} // namespace blink
+
+#endif // StyleChangeReason_h