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

chrome/browser/chrome_browser_application_mac.mm

Index: chrome/browser/chrome_browser_application_mac.mm
diff --git a/chrome/browser/chrome_browser_application_mac.mm b/chrome/browser/chrome_browser_application_mac.mm
index c4988324f14986a53a346e4f58857e53c9304ae4..a34695c4395d1d8becfb481867eae05a37eda1ea 100644
--- a/chrome/browser/chrome_browser_application_mac.mm
+++ b/chrome/browser/chrome_browser_application_mac.mm
@@ -17,6 +17,7 @@
 #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
@@ -477,7 +478,8 @@ void SwizzleInit() {
          !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();
         }
       }