Delete the temporary file when generating MHTML with the extension API.

chrome/test/base/ui_test_utils.h

Index: chrome/test/base/ui_test_utils.h
diff --git a/chrome/test/base/ui_test_utils.h b/chrome/test/base/ui_test_utils.h
index 9c5b0bec1fc83fa7fe2f86a08cc437efb66d8308..c84f2840a9f0616e0d86899870b0ada0d53906f1 100644
--- a/chrome/test/base/ui_test_utils.h
+++ b/chrome/test/base/ui_test_utils.h
@@ -18,6 +18,7 @@
 #include "base/string16.h"
 #include "chrome/browser/ui/view_ids.h"
 #include "chrome/test/automation/dom_element_proxy.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/notification_details.h"
@@ -83,6 +84,10 @@ void RunMessageLoop();
 // all pending tasks.
 void RunAllPendingInMessageLoop();
 
+// Blocks the current thread until all the pending messages in the loop of the
+// thread |thread_id| have been processed.
+void RunAllPendingInMessageLoop(content::BrowserThread::ID thread_id);
+
 // Puts the current tab title in |title|. Returns true on success.
 bool GetCurrentTabTitle(const Browser* browser, string16* title);