Specify clip rects when drawing Mac native widgets

Source/platform/mac/ThemeMac.h

Index: Source/platform/mac/ThemeMac.h
diff --git a/Source/platform/mac/ThemeMac.h b/Source/platform/mac/ThemeMac.h
index 1e215e78da5b00d1e8b12c00f68d2cb0c5ee9072..d376b2fbce22e615a3f14ae8b169a82db3e05570 100644
--- a/Source/platform/mac/ThemeMac.h
+++ b/Source/platform/mac/ThemeMac.h
@@ -54,6 +54,20 @@ public:
     virtual void paint(ControlPart, ControlStates, GraphicsContext*, const IntRect&, float zoomFactor, ScrollView*) const;
     virtual void inflateControlPaintRect(ControlPart, ControlStates, IntRect&, float zoomFactor) const;
 
+    // Inflate an IntRect to accout for specific padding around margins.
+    enum {
+        TopMargin = 0,
+        RightMargin = 1,
+        BottomMargin = 2,
+        LeftMargin = 3
+    };
+    static PLATFORM_EXPORT IntRect inflateRect(const IntRect&, const IntSize&, const int* margins, float zoomLevel = 1.0f);
+
+    // Inflate an IntRect to account for its focus ring. This is only used when
+    // BUTTON_CELL_DRAW_WITH_FRAME_DRAWS_FOCUS_RING is defined (otherwise, the focus ring's
+    // bounds could be accurately computed with -[NSCell focusRingMaskBoundsForFrame:inView:]).
+    static PLATFORM_EXPORT IntRect inflateRectForFocusRing(const IntRect&);
+
     // FIXME: Once RenderThemeMac is converted over to use Theme then this can be internal to ThemeMac.
     static NSView* ensuredView(ScrollView*);
     static void setFocusRingClipRect(const FloatRect&);