MacViews: Allow views::Widgets to be parented off NSWindows

ui/views/cocoa/bridged_native_widget_owner.h

Index: ui/views/cocoa/bridged_native_widget_owner.h
diff --git a/ui/views/cocoa/bridged_native_widget_owner.h b/ui/views/cocoa/bridged_native_widget_owner.h
new file mode 100644
index 0000000000000000000000000000000000000000..9869ed5a93869301df03c9b5b22d3ee2d2530dda
--- /dev/null
+++ b/ui/views/cocoa/bridged_native_widget_owner.h
@@ -0,0 +1,44 @@
+// 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 UI_VIEWS_COCOA_BRIDGED_NATIVE_WIDGET_OWNER_H_
+#define UI_VIEWS_COCOA_BRIDGED_NATIVE_WIDGET_OWNER_H_
+
+namespace gfx {
+class Vector2d;
+}
+
+@class NSWindow;
+
+namespace views {
+
+class BridgedNativeWidget;
+
+// An abstract interface wrapping an NSWindow that ties the lifetime of one or
+// more child BridgedNativeWidgets to the lifetime of that NSWindow. This is not
+// simply an NSWindow, because the child window API provided by NSWindow
+// requires child windows to always be visible.
+class BridgedNativeWidgetOwner {
+ public:
+  // The NSWindow parent.
+  virtual NSWindow* GetNSWindow() = 0;
+
+  // The offset in screen pixels for positioning child windows owned by |this|.
+  virtual gfx::Vector2d GetChildWindowOffset() const = 0;
+
+  // Return false if |this| is hidden, or has a hidden ancestor.
+  virtual bool IsVisibleParent() const = 0;
+
+  // Removes a child window. Note |this| may be deleted after calling, so the
+  // caller should immediately null out the pointer used to make the call.
+  virtual void RemoveChildWindow(BridgedNativeWidget* child) = 0;
+
+ protected:
+  // Instances of this class may be self-deleting.
+  virtual ~BridgedNativeWidgetOwner() {}
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_COCOA_BRIDGED_NATIVE_WIDGET_OWNER_H_