First step in enabling creating tabs without an Activity on Android.

content/browser/service_worker/service_worker_version.cc

Index: content/browser/service_worker/service_worker_version.cc
diff --git a/content/browser/service_worker/service_worker_version.cc b/content/browser/service_worker/service_worker_version.cc
index f28609efbce01fdb31087dcff923ecaf0c3b0d14..4d0cd0bfdf0bb6570f540f5c201278a3858555a8 100644
--- a/content/browser/service_worker/service_worker_version.cc
+++ b/content/browser/service_worker/service_worker_version.cc
@@ -210,6 +210,13 @@ class WindowOpenedObserver : public WebContentsObserver {
   DISALLOW_COPY_AND_ASSIGN(WindowOpenedObserver);
 };
 
+void DidOpenWindowOnUI(
+    const WindowOpenedCallback& callback, WebContents* web_contents) {
+  DCHECK(web_contents);
+
+  new WindowOpenedObserver(web_contents, callback);
+}
+
 void OpenWindowOnUI(
     const GURL& url,
     const GURL& script_url,
@@ -241,11 +248,9 @@ void OpenWindowOnUI(
                        ui::PAGE_TRANSITION_AUTO_TOPLEVEL,
                        false);
 
-  WebContents* web_contents =
-      GetContentClient()->browser()->OpenURL(browser_context, params);
-  DCHECK(web_contents);
-
-  new WindowOpenedObserver(web_contents, callback);
+  GetContentClient()->browser()->OpenURL(
+      browser_context, params,
+      base::Bind(&DidOpenWindowOnUI, callback));
 }
 
 void KillEmbeddedWorkerProcess(int process_id, ResultCode code) {