mac: Add overscroll animator slider

content/browser/web_contents/web_contents_view_overscroll_animator_slider_mac.h

+// Copyright 2014 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 CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_VIEW_OVERSCROLL_ANIMATOR_SLIDER_MAC_H_
+#define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_VIEW_OVERSCROLL_ANIMATOR_SLIDER_MAC_H_
+
+#include "base/mac/scoped_nsobject.h"
+#include "base/memory/scoped_ptr.h"
+#import <Cocoa/Cocoa.h>
+#include "content/browser/web_contents/web_contents_view_overscroll_animator_mac.h"

[Avi (use Gerrit), 2014/06/06 23:09:44]

C headers, then C++ headers, then Chrome headers. <Cocoa/Cocoa.h> goes in its
own section before all the others.

[erikchen, 2014/06/07 00:34:03]

I've moved <Cocoa/Cocoa.h> to the top, and kept the order of the rest the same,
as per your instructions.

+
+namespace content {
+class WebContentsPaintObserver;
+}
+
+@interface OverscrollAnimatorSliderView
+    : NSView<WebContentsOverscrollAnimator> {
+  // This container view holds the RenderWidgetHost's NativeViews. Most of the
+  // time, it's frame in screen coordinates is the same as SliderView's frame in

[Avi (use Gerrit), 2014/06/06 23:09:44]

s/it's/its/

[erikchen, 2014/06/07 00:34:04]

Done.

+  // screen coordinates. During an overscroll animation, it may temporarily be
+  // relocated, but it will return to its original position after the overscroll
+  // animation is finished.
+  base::scoped_nsobject<NSView> middleView_;
+
+  // This view is a sibling of middleView_, and is guaranteed to live below it.
+  // Most of the time, it is hidden. During an overscroll animation to the left,
+  // middleView_ is slid to the right, and bottomView_ peeks out from the
+  // original position of middleView_.
+  base::scoped_nsobject<NSImageView> bottomView_;
+
+  // This view is a sibling of middleView_, and is guaranteed to live above it.
+  // Most of the time, it is hidden. During an overscroll animation to the
+  // right, topView_ is slid to the left from off screen, its final position
+  // exactly covering middleView_.

[Avi (use Gerrit), 2014/06/06 23:09:44]

I must admit that I don't get these two comments. During an overscroll animation
to the left, why would things be moving to the right, and vice-versa?

[erikchen, 2014/06/07 00:34:04]

After the rename to use directions instead of left/right, the comments make a
lot more sense.

+  base::scoped_nsobject<NSImageView> topView_;
+
+  // Indicates whether the current overscroll animation is to the left or the
+  // right. This property has no meaning when inOverscroll_ is false.
+  BOOL slidingLeft_;

[Avi (use Gerrit), 2014/06/06 23:09:44]

Same comment about an enum for here.

[erikchen, 2014/06/07 00:34:03]

Ditto.

+
+  // Indicates that this view is completing or cancelling the overscroll. This
+  // animation cannot be cancelled.
+  BOOL animating_;
+
+  // Reflects whether this view is in the process of handling an overscroll.
+  BOOL inOverscroll_;
+
+  // The most recent value passed to -updateOverscrollProgress:.
+  CGFloat progress_;
+
+  // An observer that reports the first non-empty paint of a WebContents. This
+  // is used when completing an overscroll animation.
+  scoped_ptr<content::WebContentsPaintObserver> observer_;
+}
+@end
+
+#endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_VIEW_OVERSCROLL_ANIMATOR_SLIDER_MAC_H_