Move ui_test_utils::CrashTab to browser_test_utils so that it can be reused by content_browsertests.

chrome/test/base/ui_test_utils.cc

Index: chrome/test/base/ui_test_utils.cc
===================================================================
--- chrome/test/base/ui_test_utils.cc	(revision 148487)
+++ chrome/test/base/ui_test_utils.cc	(working copy)
@@ -360,15 +360,6 @@
   return content::Source<AppModalDialog>(observer.source()).ptr();
 }
 
-void CrashTab(WebContents* tab) {
-  content::RenderProcessHost* rph = tab->GetRenderProcessHost();
-  content::WindowedNotificationObserver observer(
-      content::NOTIFICATION_RENDERER_PROCESS_CLOSED,
-      content::Source<content::RenderProcessHost>(rph));
-  base::KillProcess(rph->GetHandle(), 0, false);
-  observer.Wait();
-}
-
 int FindInPage(TabContents* tab_contents, const string16& search_string,
                bool forward, bool match_case, int* ordinal) {
   tab_contents->