Always set NSTexturedBackgroundWindowMask on app windows.

chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h

Index: chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h
diff --git a/chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h b/chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h
index 095e209fa399aba4c29ee46d53af928e75b445cb..fc9f119bcd4b03a3c3cb4c8d4f887e3381f42774 100644
--- a/chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h
+++ b/chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h
@@ -168,9 +168,7 @@ class NativeAppWindowCocoa : public apps::NativeAppWindow,
   content::WebContents* WebContents() const;
 
   // Returns the WindowStyleMask based on the type of window frame.
-  // Specifically, this includes NSResizableWindowMask if the window is
-  // resizable, and does not include NSTexturedBackgroundWindowMask when a
-  // native frame is used.
+  // This includes NSResizableWindowMask if the window is resizable.
   NSUInteger GetWindowStyleMask() const;
 
   void InstallView();