Define Panning cursors only on Windows

ui/base/cursor/cursor.h

Index: ui/base/cursor/cursor.h
diff --git a/ui/base/cursor/cursor.h b/ui/base/cursor/cursor.h
index 72999d4c3be41e8cfc65a694a63129f555d60ec6..8991de904eabfd018469a8b283164de934112447 100644
--- a/ui/base/cursor/cursor.h
+++ b/ui/base/cursor/cursor.h
@@ -57,6 +57,8 @@ const int kCursorNorthEastSouthWestResize = 17;
 const int kCursorNorthWestSouthEastResize = 18;
 const int kCursorColumnResize = 19;
 const int kCursorRowResize = 20;
+#if defined(OS_WIN)
+// These cursors are for Windows' pan-scrolling.
 const int kCursorMiddlePanning = 21;
 const int kCursorEastPanning = 22;
 const int kCursorNorthPanning = 23;
@@ -66,6 +68,7 @@ const int kCursorSouthPanning = 26;
 const int kCursorSouthEastPanning = 27;
 const int kCursorSouthWestPanning = 28;
 const int kCursorWestPanning = 29;
+#endif
 const int kCursorMove = 30;
 const int kCursorVerticalText = 31;
 const int kCursorCell = 32;