Rejigger ThemeService: move exposure of ThemeProvider interface to a

chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm

 // Copyright (c) 2012 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.
 
 #import "chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.h"
 
 #include <utility>
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/mac/scoped_nsobject.h"
@@ skipping 91 matching lines @@
 // view.
 - (void)delegateDestroyed {
   delegate_ = nil;
 }
 
 - (NSColor*)computeBackgroundColor {
   // This view is sometimes flashed into visibility (e.g, when closing
   // windows or opening new tabs), so ensure that the flash be the theme
   // background color in those cases.
   NSColor* backgroundColor = nil;
-  ThemeService* const theme =
-      static_cast<ThemeService*>([[self window] themeProvider]);
+  ui::ThemeProvider* const theme = [[self window] themeProvider];
   if (theme)
     backgroundColor = theme->GetNSColor(ThemeProperties::COLOR_NTP_BACKGROUND);
   if (!backgroundColor)
     backgroundColor = [NSColor whiteColor];
 
   // If the page is in fullscreen tab capture mode, change the background color
   // to be a dark tint of the new tab page's background color.
   if ([delegate_ contentsInFullscreenCaptureMode]) {
     const float kDarknessFraction = 0.80f;
     return [backgroundColor blendedColorWithFraction:kDarknessFraction
@@ skipping 223 matching lines @@
     } else {
       rect.ClampToCenteredSize(gfx::Size(
           static_cast<int>(x / captureSize.height()), rect.height()));
     }
   }
 
   return NSRectFromCGRect(rect.ToCGRect());
 }
 
 @end