Allow a View to specify a non-default native theme (i.e. different from

ui/views/view.h

 // Copyright (c) 2012 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_VIEW_H_
 #define UI_VIEWS_VIEW_H_
 
 #include <stddef.h>
 
 #include <algorithm>
@@ skipping 521 matching lines @@
   // The border object is owned by this object and may be NULL.
   virtual void SetBorder(std::unique_ptr<Border> b);
   const Border* border() const { return border_.get(); }
   Border* border() { return border_.get(); }
 
   // Get the theme provider from the parent widget.
   const ui::ThemeProvider* GetThemeProvider() const;
 
   // Returns the NativeTheme to use for this View. This calls through to
   // GetNativeTheme() on the Widget this View is in, or provides a default
-  // theme if there's no widget. Warning: the default theme might not be
-  // correct; you should probably override OnNativeThemeChanged().
+  // theme if there's no widget, or returns |native_theme_override_| if that's
+  // set. Warning: the default theme might not be correct; you should probably
+  // override OnNativeThemeChanged().
   ui::NativeTheme* GetNativeTheme() {
     return const_cast<ui::NativeTheme*>(
         const_cast<const View*>(this)->GetNativeTheme());
   }
   const ui::NativeTheme* GetNativeTheme() const;
 
+  // Sets the native theme override and informs descendants.

[sky, 2017/01/09 16:13:52]

I'm not sure 'override' buys much here. How about SetNativeTheme ? Similar
comment for the member name, native_theme_ is fine.

[Evan Stade, 2017/01/09 17:36:26]

Done.

+  void SetNativeThemeOverride(ui::NativeTheme* theme);
+
   // RTL painting --------------------------------------------------------------
 
   // This method determines whether the gfx::Canvas object passed to
   // View::Paint() needs to be transformed such that anything drawn on the
   // canvas object during View::Paint() is flipped horizontally.
   bool flip_canvas_on_paint_for_rtl_ui() const {
     return flip_canvas_on_paint_for_rtl_ui_;
   }
 
   // Enables or disables flipping of the gfx::Canvas during View::Paint().
@@ skipping 980 matching lines @@
 
   // Background
   std::unique_ptr<Background> background_;
 
   // Border.
   std::unique_ptr<Border> border_;
 
   // Cached output of painting to be reused in future frames until invalidated.
   ui::PaintCache paint_cache_;
 
+  // Native theme --------------------------------------------------------------
+
+  // A non-default native theme for this view and its descendants. When null,
+  // the native theme is drawn from the parent view (eventually the widget).
+  ui::NativeTheme* native_theme_override_ = nullptr;
+
   // RTL painting --------------------------------------------------------------
 
   // Indicates whether or not the gfx::Canvas object passed to View::Paint()
   // is going to be flipped horizontally (using the appropriate transform) on
   // right-to-left locales for this View.
   bool flip_canvas_on_paint_for_rtl_ui_;
 
   // Accelerated painting ------------------------------------------------------
 
   bool paint_to_layer_;
@@ skipping 42 matching lines @@
   // Observers -------------------------------------------------------------
 
   base::ObserverList<ViewObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(View);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEW_H_