MacViews: Overlay Scrollbars with Show/Hide Animations

ui/views/cocoa/views_scrollbar_bridge.h

+// Copyright 2016 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 UI_VIEWS_COCOA_VIEWS_SCROLLBAR_BRIDGE_DELEGATE_H_
+#define UI_VIEWS_COCOA_VIEWS_SCROLLBAR_BRIDGE_DELEGATE_H_
+
+#import <Cocoa/Cocoa.h>
+
+#import "base/mac/scoped_nsobject.h"
+#include "ui/views/views_export.h"
+
+// The delegate set to ViewsScrollbarBridge.
+class ViewsScrollbarBridgeDelegate {
+ public:
+  virtual void OnScrollerStyleChanged() = 0;

[tapted, 2016/02/11 08:46:17]

nit: needs a comment. I'd say something like, `Invoked when the system informs
the process that the preferred scroller style has changed (e.g. external mouse
plugged in, or changed in System Preferences).

[spqchan, 2016/02/13 01:39:23]

Done.

+};
+
+// A bridge to NSScroller managed by NativeCocoaScrollbar. Serves as a helper
+// class to bridge NSScroller notifications and functions to
+// NativeCocoaScrollbar.
+@interface ViewsScrollbarBridge : NSObject {
+ @private
+  ViewsScrollbarBridgeDelegate* delegate_;  // Weak. Owns this.
+}
+
+// Sets the |delegate|.
+- (void)setDelegate:(ViewsScrollbarBridgeDelegate*)delegate;
+
+// Returns the style of scrollers that OSX is using.
+- (NSScrollerStyle)getPreferredScrollerStyle;

[tapted, 2016/02/11 08:46:17]

+ class function?

[spqchan, 2016/02/13 01:39:23]

Done.

+
+@end
+
+#endif