Make JavaScript dialogs auto-dismiss on tab switch.

components/app_modal/javascript_dialog_manager.cc

Index: components/app_modal/javascript_dialog_manager.cc
diff --git a/components/app_modal/javascript_dialog_manager.cc b/components/app_modal/javascript_dialog_manager.cc
index 7628f213971b00f14c59ec058dd2c1b7dc228e99..fbe828a0403a4dc88de7dda84dc59af2c36d733b 100644
--- a/components/app_modal/javascript_dialog_manager.cc
+++ b/components/app_modal/javascript_dialog_manager.cc
@@ -150,8 +150,7 @@ void JavaScriptDialogManager::RunJavaScriptDialog(
     last_close_time_ = base::TimeTicks();
   }
 
-  bool is_alert = message_type == content::JAVASCRIPT_MESSAGE_TYPE_ALERT;
-  base::string16 dialog_title = GetTitle(web_contents, origin_url, is_alert);
+  base::string16 dialog_title = GetTitle(web_contents, origin_url);
 
   extensions_client_->OnDialogOpened(web_contents);
 
@@ -243,8 +242,7 @@ bool JavaScriptDialogManager::HandleJavaScriptDialog(
 
 base::string16 JavaScriptDialogManager::GetTitle(
     content::WebContents* web_contents,
-    const GURL& origin_url,
-    bool is_alert) {
+    const GURL& origin_url) {
   // For extensions, show the extension name, but only if the origin of
   // the alert matches the top-level WebContents.
   std::string name;