Mac: Prevent NTP mousewheel events from being suppressed on Lion.

base/mac/mac_util.mm

Index: base/mac/mac_util.mm
diff --git a/base/mac/mac_util.mm b/base/mac/mac_util.mm
index ad735968f35d50c9d8fab0c9d059f4e7af1fa115..4b9cc8b4336b6fe79429b79d04c4df0c815a1fe5 100644
--- a/base/mac/mac_util.mm
+++ b/base/mac/mac_util.mm
@@ -21,6 +21,17 @@
 #include "base/string_piece.h"
 #include "base/sys_string_conversions.h"
 
+#if !defined(MAC_OS_X_VERSION_10_7) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
+
+// Declare symbols that are part of the 10.7 SDK.
+
+@interface NSEvent (LionSDKDeclarations)
++ (bool)isSwipeTrackingFromScrollEventsEnabled;
+@end
+
+#endif  // MAC_OS_X_VERSION_10_7
+
 namespace base {
 namespace mac {
 
@@ -696,5 +707,11 @@ bool ParseModelIdentifier(const std::string& ident,
   return true;
 }
 
+bool IsSwipeTrackingFromScrollEventsEnabled() {
+  return [NSEvent respondsToSelector:@selector(
+              isSwipeTrackingFromScrollEventsEnabled)]
+      && [NSEvent isSwipeTrackingFromScrollEventsEnabled];
+}
+
 }  // namespace mac
 }  // namespace base