Cleanup: Remove more uses of Browser::tabstrip_model().

chrome/browser/ui/views/frame/browser_view.cc

Index: chrome/browser/ui/views/frame/browser_view.cc
===================================================================
--- chrome/browser/ui/views/frame/browser_view.cc	(revision 120097)
+++ chrome/browser/ui/views/frame/browser_view.cc	(working copy)
@@ -1397,7 +1397,7 @@
   // We use index here rather than comparing |contents| because by this time
   // the model has already removed |contents| from its list, so
   // browser_->GetSelectedWebContents() will return NULL or something else.
-  if (index == browser_->tabstrip_model()->active_index()) {
+  if (index == browser_->active_index()) {
     // We need to reset the current tab contents to NULL before it gets
     // freed. This is because the focus manager performs some operations
     // on the selected TabContents when it is removed.