[MacViews] Frameless app windows: make content view cover title bar.

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

+// Copyright 2015 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.
+
+#include "chrome/browser/ui/views/apps/app_window_native_widget_mac.h"
+
+#import <Cocoa/Cocoa.h>
+
+#import "chrome/browser/ui/views/apps/native_widget_mac_frameless_nswindow.h"
+#import "ui/base/cocoa/window_size_constants.h"
+
+AppWindowNativeWidgetMac::AppWindowNativeWidgetMac(views::Widget* widget)
+    : NativeWidgetMac(widget) {
+}
+
+AppWindowNativeWidgetMac::~AppWindowNativeWidgetMac() {
+}
+
+NSWindow* AppWindowNativeWidgetMac::CreateNSWindow(
+    const views::Widget::InitParams& params) {
+  // If the window has a standard frame, use the same NSWindow as
+  // NativeWidgetMac.
+  if (!params.remove_standard_frame)
+    return NativeWidgetMac::CreateNSWindow(params);
+
+  // NSTexturedBackgroundWindowMask is needed to implement draggable window
+  // regions.
+  NSUInteger style_mask = NSTexturedBackgroundWindowMask | NSTitledWindowMask |
+                          NSClosableWindowMask | NSMiniaturizableWindowMask |
+                          NSResizableWindowMask;
+  return [[[NativeWidgetMacFramelessNSWindow alloc]
+      initWithContentRect:ui::kWindowSizeDeterminedLater
+                styleMask:style_mask
+                  backing:NSBackingStoreBuffered
+                    defer:YES] autorelease];
+}