[Mac] Use a custom view to implement colored app windows.

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

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_APPS_NATIVE_APP_WINDOW_COCOA_H_
 #define CHROME_BROWSER_UI_COCOA_APPS_NATIVE_APP_WINDOW_COCOA_H_
 
 #import <Cocoa/Cocoa.h>
 #include <vector>
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #import "chrome/browser/ui/cocoa/browser_command_executor.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "extensions/browser/app_window/app_window.h"
 #include "extensions/browser/app_window/native_app_window.h"
 #include "extensions/browser/app_window/size_constraints.h"
 #include "extensions/common/draggable_region.h"
 #include "ui/base/accelerators/accelerator_manager.h"
 #include "ui/gfx/geometry/rect.h"
 
 class ExtensionKeybindingRegistryCocoa;
 class NativeAppWindowCocoa;
 @class ShellNSWindow;
 class SkRegion;
+@class TitlebarBackgroundView;
 
 // A window controller for a minimal window to host a web app view. Passes
 // Objective-C notifications to the C++ bridge.
 @interface NativeAppWindowController : NSWindowController
                                       <NSWindowDelegate,
                                        BrowserCommandExecutor> {
  @private
   NativeAppWindowCocoa* appWindow_;  // Weak; owns self.
 }
 
@@ skipping 163 matching lines @@
   bool shows_resize_controls_;
   bool shows_fullscreen_controls_;
 
   extensions::SizeConstraints size_constraints_;
 
   bool has_frame_color_;
   SkColor active_frame_color_;
   SkColor inactive_frame_color_;
 
   base::scoped_nsobject<NativeAppWindowController> window_controller_;
+  base::scoped_nsobject<TitlebarBackgroundView> titlebar_background_view_;
 
   // For system drag, the whole window is draggable and the non-draggable areas
   // have to been explicitly excluded.
   std::vector<extensions::DraggableRegion> draggable_regions_;
 
   // The Extension Command Registry used to determine which keyboard events to
   // handle.
   scoped_ptr<ExtensionKeybindingRegistryCocoa> extension_keybinding_registry_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeAppWindowCocoa);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_APPS_NATIVE_APP_WINDOW_COCOA_H_