[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>
 
@@ skipping 25 matching lines @@
 @property(assign, nonatomic) NativeAppWindowCocoa* appWindow;
 
 // Consults the Command Registry to see if this |event| needs to be handled as
 // an extension command and returns YES if so (NO otherwise).
 // Only extensions with the given |priority| are considered.
 - (BOOL)handledByExtensionCommand:(NSEvent*)event
     priority:(ui::AcceleratorManager::HandlerPriority)priority;
 
 @end
 
+// A view that paints a solid color. Used to change the title bar background.
+@interface TitlebarBackgroundView : NSView {

[tapted, 2015/02/19 03:11:02]

forward declare this? i.e. just `@class TitlebarBackgroundView;`

[jackhou1, 2015/02/19 04:28:58]

Done.

+ @private
+  base::scoped_nsobject<NSColor> color_;
+  base::scoped_nsobject<NSColor> inactiveColor_;
+}
+- (void)setColor:(NSColor*)color
+   inactiveColor:(NSColor*)inactiveColor;

[tapted, 2015/02/19 03:11:02]

nit: minimum 4 space indent (colons are allowed to misalign in this case)

[jackhou1, 2015/02/19 04:28:58]

Done.

+@end
+
 // Cocoa bridge to AppWindow.
 class NativeAppWindowCocoa : public extensions::NativeAppWindow,
                              public content::WebContentsObserver {
  public:
   NativeAppWindowCocoa(extensions::AppWindow* app_window,
                        const extensions::AppWindow::CreateParams& params);
 
   // ui::BaseWindow implementation.
   bool IsActive() const override;
   bool IsMaximized() const override;
@@ skipping 143 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_