[MacViews] Implement AlwaysOnTop and VisibleOnAllWorkspaces.

ui/gfx/mac/nswindow_frame_controls.h

Index: ui/gfx/mac/nswindow_frame_controls.h
diff --git a/ui/gfx/mac/nswindow_frame_controls.h b/ui/gfx/mac/nswindow_frame_controls.h
index 7ec7ab7ee0f6b7aecb549f422c51682a4d218c55..61c6331ecfa51f37b6e4a0008aacc52f24150b4c 100644
--- a/ui/gfx/mac/nswindow_frame_controls.h
+++ b/ui/gfx/mac/nswindow_frame_controls.h
@@ -17,6 +17,20 @@ class Size;
 GFX_EXPORT void SetNSWindowCanFullscreen(NSWindow* window,
                                          bool allow_fullscreen);
 
+// Returns whether the window is always-on-top.
+GFX_EXPORT bool IsNSWindowAlwaysOnTop(NSWindow* window);
+
+// Sets whether the window is always-on-top. This also sets
+// NSWindowCollectionBehaviorManaged because by default always-on-top windows
+// are NSWindowCollectionBehaviorTransient which means they will not appear in
+// Expose and cannot be moved between workspaces.
+GFX_EXPORT void SetNSWindowAlwaysOnTop(NSWindow* window,
+                                       bool always_on_top);
+
+// Sets whether the window appears on all workspaces.
+GFX_EXPORT void SetNSWindowVisibleOnAllWorkspaces(NSWindow* window,
+                                                  bool always_visible);
+
 // Sets the min/max size of the window as well as showing/hiding resize,
 // maximize, and fullscreen controls.
 // Sizes refer to the content size (inner bounds).