Theme delegate fixes for the 10.6 SDK folllowing r43708....

chrome/browser/cocoa/chrome_browser_window.mm

 // Copyright (c) 2009 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/cocoa/chrome_browser_window.h"
 
 #include "base/logging.h"
 #include "chrome/browser/browser_theme_provider.h"
 #import "chrome/browser/cocoa/browser_frame_view.h"
 #import "chrome/browser/cocoa/browser_window_controller.h"
@@ skipping 326 matching lines @@
   // return the original (unconstrained) frame.
   id delegate = [self delegate];
   if ([delegate respondsToSelector:@selector(shouldConstrainFrameRect)] &&
       ![delegate shouldConstrainFrameRect])
     return frame;
 
   return [super constrainFrameRect:frame toScreen:screen];
 }
 
 - (ThemeProvider*)themeProvider {
-  return [[self delegate] themeProvider];
+  id delegate = [self delegate];
+  if (![delegate respondsToSelector:@selector(themeProvider)])
+    return NULL;
+  return [delegate themeProvider];
 }
 
 - (ThemedWindowStyle)themedWindowStyle {
-  return [[self delegate] themedWindowStyle];
+  id delegate = [self delegate];
+  if (![delegate respondsToSelector:@selector(themedWindowStyle)])
+    return THEMED_NORMAL;
+  return [delegate themedWindowStyle];
 }
 
 - (NSPoint)themePatternPhase {
-  return [[self delegate] themePatternPhase];
+  id delegate = [self delegate];
+  if (![delegate respondsToSelector:@selector(themePatternPhase)])
+    return NSMakePoint(0, 0);
+  return [delegate themePatternPhase];
 }
 
 @end