Clean up TCW, make it solely a hub for 1:1 observer/helper objects.

chrome/browser/chrome_browser_application_mac.mm

 // 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.
 
 #import "chrome/browser/chrome_browser_application_mac.h"
 
 #import "base/logging.h"
 #include "base/mac/crash_logging.h"
 #import "base/mac/scoped_nsexception_enabler.h"
 #import "base/metrics/histogram.h"
 #import "base/memory/scoped_nsobject.h"
 #import "base/sys_string_conversions.h"
 #import "chrome/browser/app_controller_mac.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
 #import "chrome/common/mac/objc_method_swizzle.h"
 #import "chrome/common/mac/objc_zombie.h"
 #include "content/browser/accessibility/browser_accessibility_state.h"
 #include "content/browser/renderer_host/render_view_host.h"
+#include "content/browser/tab_contents/tab_contents.h"
 
 // The implementation of NSExceptions break various assumptions in the
 // Chrome code.  This category defines a replacement for
 // -initWithName:reason:userInfo: for purposes of forcing a break in
 // the debugger when an exception is raised.  -raise sounds more
 // obvious to intercept, but it doesn't catch the original throw
 // because the objc runtime doesn't use it.
 @interface NSException (CrNSExceptionSwizzle)
 - (id)crInitWithName:(NSString*)aName
               reason:(NSString*)aReason
@@ skipping 440 matching lines @@
 }
 
 - (void)accessibilitySetValue:(id)value forAttribute:(NSString*)attribute {
   if ([attribute isEqualToString:@"AXEnhancedUserInterface"] &&
       [value intValue] == 1) {
     BrowserAccessibilityState::GetInstance()->OnScreenReaderDetected();
     for (TabContentsIterator it;
          !it.done();
          ++it) {
       if (TabContentsWrapper* contents = *it) {
-        if (RenderViewHost* rvh = contents->render_view_host()) {
+        if (RenderViewHost* rvh =
+                contents->tab_contents()->render_view_host()) {
           rvh->EnableRendererAccessibility();
         }
       }
     }
   }
   return [super accessibilitySetValue:value forAttribute:attribute];
 }
 
 @end