Add a Material Design Circular Activity Indicator (Spinner) view for Mac.

chrome/browser/ui/cocoa/circular_activity_indicator_view.h

Index: chrome/browser/ui/cocoa/circular_activity_indicator_view.h
diff --git a/chrome/browser/ui/cocoa/circular_activity_indicator_view.h b/chrome/browser/ui/cocoa/circular_activity_indicator_view.h
new file mode 100644
index 0000000000000000000000000000000000000000..aeeff61618d53e7b1662a5d8f66f2883e640dd73
--- /dev/null
+++ b/chrome/browser/ui/cocoa/circular_activity_indicator_view.h
@@ -0,0 +1,22 @@
+// Copyright 2015 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 CHROME_BROWSER_UI_COCOA_CIRCULAR_ACTIVITY_INDICATOR_VIEW_H_
+#define CHROME_BROWSER_UI_COCOA_CIRCULAR_ACTIVITY_INDICATOR_VIEW_H_
+
+#import <Cocoa/Cocoa.h>
+#import <QuartzCore/QuartzCore.h>

[groby-ooo-7-16, 2015/03/30 23:28:30]

Can you forward-declare @class CAShapeLayer/CAAnimationGroup and include the
header in the .mm file?

[shrike, 2015/03/31 07:05:53]

Done.

+
+#include "base/mac/scoped_nsobject.h"
+
+@interface CircularActivityIndicatorView : NSView
+{
+  base::scoped_nsobject<CAAnimationGroup> spinner_animation_;

[groby-ooo-7-16, 2015/03/30 23:28:30]

General question: I assume we ruled out using ui/gfx/animation.h because we lose
GPU acceleration?

[groby-ooo-7-16, 2015/03/30 23:28:30]

Can we move the ivars to the implementation?

[shrike, 2015/03/31 07:05:53]

This class is patterned after sprite_view. I have made the change, but
sprite_view's equivalent code defines them in the .h.

Except, the unit tests need is_animating_ exposed. Not sure if I should expose
the ivar or add API (is_animating) that will only be used by the unit tests.

[shrike, 2015/03/31 07:05:53]

This appears to be timer-based animation, which would incur an energy penalty
for timer usage, plus incur CPU usage (vs. this GPU-based Core Animation code).

+  CAShapeLayer* shape_layer_;

[groby-ooo-7-16, 2015/03/30 23:28:30]

Personal nit: I like a // Weak. comment at the end of unowned/non-refcounted
objects. It's optional, but I think it makes things slightly clearer when
non-Cocoa people read the code.

[shrike, 2015/03/31 07:05:53]

Done.

+  bool is_animating_;
+}
+
+@end
+
+#endif  // CHROME_BROWSER_UI_COCOA_CIRCULAR_ACTIVITY_INDICATOR_VIEW_H_