Fix top crash due to r110394 - TabContentsViewCocoa renderWidgetHostWasResized

crashes due to a NULL tabContents pointer.

BUG=104751
TEST=no

Review URL: http://codereview.chromium.org/8586056

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110768 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/tab_contents/tab_contents_view_mac.mm

@@ -519,7 +519,7 @@ void TabContentsViewMac::CloseTab() {
 
 - (void)renderWidgetHostWasResized {
   TabContents* tabContents = [self tabContents];
-  if (tabContents->render_view_host())
+  if (tabContents && tabContents->render_view_host())
     tabContents->render_view_host()->WasResized();
 }