Pass a ui::PaintContext from ui::Layer to layer delegates.

ui/wm/core/image_grid.h

Index: ui/wm/core/image_grid.h
diff --git a/ui/wm/core/image_grid.h b/ui/wm/core/image_grid.h
index f58ffbb5381607e939fe6dd68d9dab5ffe837348..3bd46baacbab6bc97d5d1a3d6821c371ede8b439 100644
--- a/ui/wm/core/image_grid.h
+++ b/ui/wm/core/image_grid.h
@@ -137,7 +137,7 @@ class WM_EXPORT ImageGrid {
     void SetClipRect(const gfx::Rect& clip_rect, ui::Layer* layer);
 
     // ui::LayerDelegate implementation:
-    void OnPaintLayer(gfx::Canvas* canvas) override;
+    void OnPaintLayer(const ui::PaintContext& context) override;
     void OnDelegatedFrameDamage(const gfx::Rect& damage_rect_in_dip) override;
     void OnDeviceScaleFactorChanged(float device_scale_factor) override;
     base::Closure PrepareForLayerBoundsChange() override;