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 198a02dc76fd9eda28070fecb227b64b620fac9a..17ded798c990a7f930c5423dff5cfe1ebc4948f5 100644
--- a/content/browser/service_worker/service_worker_version.cc
+++ b/content/browser/service_worker/service_worker_version.cc
@@ -219,6 +219,13 @@ class WindowOpenedObserver : public WebContentsObserver {
   DISALLOW_COPY_AND_ASSIGN(WindowOpenedObserver);
 };
 
+void DidOpenWindowOnUI(

[mlamouri (slow - plz ping), 2015/02/09 12:07:37]

nit: DidOpenURL would be the right name for a callback called by OpenURL.
Specifying "OnUI" would be confusing because that naming convention is usually
used when there is an associated method on another thread.

[Peter Beverloo, 2015/02/10 17:49:37]

Done.

+    const WindowOpenedCallback& callback, WebContents* web_contents) {
+  DCHECK(web_contents);
+
+  new WindowOpenedObserver(web_contents, callback);
+}
+
 void OpenWindowOnUI(
     const GURL& url,
     const GURL& script_url,
@@ -250,11 +257,9 @@ void OpenWindowOnUI(
                        ui::PAGE_TRANSITION_AUTO_TOPLEVEL,
                        true /* is_renderer_initiated */);
 
-  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));

[mlamouri (slow - plz ping), 2015/02/09 12:07:37]

Alternatively, you could pass browser_context and params to
WindowOpenedObserver() and have it call OpenURL() then when the call succeeds,
start listening to the returned WebContents. Keep it as is if you don't like
that.

[Peter Beverloo, 2015/02/10 17:49:37]

I don't feel strongly about this code, so I'll leave it as it is.

 }
 
 void KillEmbeddedWorkerProcess(int process_id, ResultCode code) {