[MacViews] Implement colored window frames.

chrome/browser/ui/views/apps/app_window_native_widget_mac.h

Index: chrome/browser/ui/views/apps/app_window_native_widget_mac.h
diff --git a/chrome/browser/ui/views/apps/app_window_native_widget_mac.h b/chrome/browser/ui/views/apps/app_window_native_widget_mac.h
index ae7cfc2c4eb5d8833abddace515c30a976dac671..f7deb705bc3d27d2cabc82df076225d7c8a49ea5 100644
--- a/chrome/browser/ui/views/apps/app_window_native_widget_mac.h
+++ b/chrome/browser/ui/views/apps/app_window_native_widget_mac.h
@@ -7,11 +7,16 @@
 
 #include "ui/views/widget/native_widget_mac.h"
 
+namespace extensions {
+class NativeAppWindow;
+}
+
 // This implements features specific to app windows, e.g. frameless windows that
 // behave like normal windows.
 class AppWindowNativeWidgetMac : public views::NativeWidgetMac {
  public:
-  explicit AppWindowNativeWidgetMac(views::Widget* widget);
+  AppWindowNativeWidgetMac(views::Widget* widget,
+                           extensions::NativeAppWindow* native_app_window);
   ~AppWindowNativeWidgetMac() override;
 
  protected:
@@ -20,6 +25,10 @@ class AppWindowNativeWidgetMac : public views::NativeWidgetMac {
       const views::Widget::InitParams& params) override;
 
  private:
+  // Weak. Owned by extensions::AppWindow (which manages our Widget via its
+  // WebContents).
+  extensions::NativeAppWindow* native_app_window_;
+
   DISALLOW_COPY_AND_ASSIGN(AppWindowNativeWidgetMac);
 };