Remove VectorIconId references from the codebase

ash/system/palette/palette_tool_manager.h

Index: ash/system/palette/palette_tool_manager.h
diff --git a/ash/system/palette/palette_tool_manager.h b/ash/system/palette/palette_tool_manager.h
index e21addde94ecad2819cdc1825715ea455d76b735..001a34095980e4bc7e19904a2d77a9f93063f92d 100644
--- a/ash/system/palette/palette_tool_manager.h
+++ b/ash/system/palette/palette_tool_manager.h
@@ -82,8 +82,8 @@ class ASH_EXPORT PaletteToolManager : public PaletteTool::Delegate {
   // Returns the active tool for the given group.
   PaletteToolId GetActiveTool(PaletteGroup group);
 
-  // Fetch the active tray icon for the given tool. Returns
-  // gfx::VectorIconId::VECTOR_ICON_NONE if not available.
+  // Fetch the active tray icon for the given tool. Returns an empty icon if
+  // not available.
   const gfx::VectorIcon& GetActiveTrayIcon(PaletteToolId tool_id) const;
 
   // Create views for all of the registered tools.