Make scrollAnimatorEnabled work on Mac like it does on other platforms

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 75d53c90961086c6225b352981d181a8d5733524..02ae6265b64a7a374ecaf7c069eb633c83f701bc 100644
--- a/base/mac/mac_util.mm
+++ b/base/mac/mac_util.mm
@@ -21,6 +21,7 @@
 #include "base/mac/scoped_ioobject.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/mac/sdk_forward_declarations.h"
+#include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/sys_string_conversions.h"
@@ -603,5 +604,26 @@ bool ParseModelIdentifier(const std::string& ident,
   return true;
 }
 
+bool IsScrollAnimationEnabled() {

[Robert Sesek, 2016/02/08 17:39:51]

I don't think this needs to be in base, since it's only called in //ui/gfx. Just
create animation_mac.mm to implement ScrollAnimationsEnabledBySystem in an
ObjC++ file.

[bokan, 2016/02/08 20:55:06]

Done. I moved the Windows bits into animation_win.cc for consistency too.

+  // Because of sandboxing, OS settings should only be queried from the browser
+  // process.
+  DCHECK(base::MessageLoopForUI::IsCurrent() ||
+      base::MessageLoopForIO::IsCurrent());
+
+  bool enabled = false;
+  id value = nil;
+  if (base::mac::IsOSMountainLionOrLater()) {
+    value = [[NSUserDefaults standardUserDefaults]
+        objectForKey:@"NSScrollAnimationEnabled"];
+  } else {
+    value = [[NSUserDefaults standardUserDefaults]
+        objectForKey:@"AppleScrollAnimationEnabled"];
+  }
+  if (value)
+    enabled = [value boolValue];
+  return enabled;
+}
+
+
 }  // namespace mac
 }  // namespace base