Desktop aura: Continue threading context through views.

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index 3daac1206eb79653e358794c5e695bfae4efff6f..136ae6f572fa8d2f53a8bb8841ae20cccb9ab5c0 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -145,6 +145,10 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
     // |parent| is returned.
     gfx::NativeView GetParent() const;
 
+    // Will return the first of the following that isn't NULL: the native view,
+    // |parent|, |context|.
+    gfx::NativeView GetContext() const;
+
     Type type;
     // If NULL, a default implementation will be constructed.
     WidgetDelegate* delegate;
@@ -191,9 +195,13 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
     // Only used by NativeWidgetAura. Specifies the type of layer for the
     // aura::Window. Default is LAYER_TEXTURED.
     ui::LayerType layer_type;
-    // Only used by Aura. Provides additional context (generally a RootWindow)
-    // during creation to allow the widget to determine which desktop type it
-    // will belong to. NULL is not allowed if you are using aura.
+    // Only used by Aura. Provides a context window whose RootWindow we be
+    // consulted during widget creation to determine where in the Window
+    // hierarchy this widget should be placed. (This is separate from |parent|;
+    // if you pass a RootWindow to |parent|, your window will be parented to
+    // |parent|. If you pass a RootWindow to |context|, we ask that RootWindow
+    // where it wants your window placed.) NULL is not allowed if you are using
+    // aura.
     gfx::NativeView context;
   };