Mac: Make it easier for views to correctly draw with a theme.

chrome/browser/ui/cocoa/background_gradient_view.h

 // Copyright (c) 2011 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_BACKGROUND_GRADIENT_VIEW_H_
 #define CHROME_BROWSER_UI_COCOA_BACKGROUND_GRADIENT_VIEW_H_
 
 #import <Cocoa/Cocoa.h>
 
+#import "chrome/browser/ui/cocoa/themed_window.h"
+
 // A custom view that draws a 'standard' background gradient.
 // Base class for other Chromium views.
-@interface BackgroundGradientView : NSView {
+@interface BackgroundGradientView : NSView<ThemedWindowDrawing> {
  @private
   BOOL showsDivider_;
 }
 
 // Controls whether the bar draws a dividing line at the bottom.
 @property(nonatomic, assign) BOOL showsDivider;
 
 // The color used for the bottom stroke. Public so subclasses can use.
 - (NSColor*)strokeColor;
 
 // Draws the background for this view. Make sure that your patternphase
 // is set up correctly in your graphics context before calling.
 // If |opaque| is true then the background image is forced to be opaque.
 // Otherwise the background image could be semi-transparent and blend against
 // subviews and sublayers. This is different from -[NSView isOpaque] since
 // a view may want a opaque non-rectangular background. The find bar is an
 // example of this.
 - (void)drawBackgroundWithOpaque:(BOOL)opaque;
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_BACKGROUND_GRADIENT_VIEW_H_