Check if there is a SW controlling the start page for app banner.

content/public/browser/service_worker_context.h

Index: content/public/browser/service_worker_context.h
diff --git a/content/public/browser/service_worker_context.h b/content/public/browser/service_worker_context.h
index 22c989b4ce8254ddfd423421af59aec9cec2f69c..0d29fc6e38997c744451d31d0640a09f3e35107e 100644
--- a/content/public/browser/service_worker_context.h
+++ b/content/public/browser/service_worker_context.h
@@ -32,6 +32,9 @@ class ServiceWorkerContext {
   typedef base::Callback<void(const std::vector<ServiceWorkerUsageInfo>&
                                   usage_info)> GetUsageInfoCallback;
 
+  typedef base::Callback<void(bool has_same_service_worker)>
+      CheckHasSameServiceWorkerCallback;
+
   // Registers the header name which should not be passed to the ServiceWorker.
   // Must be called from the IO thread.
   CONTENT_EXPORT static void AddExcludedHeadersForFetchEvent(
@@ -73,7 +76,7 @@ class ServiceWorkerContext {
 
   // TODO(jyasskin): Provide a way to SendMessage to a Scope.
 
-  // Determines if a request for 'url' can be satisfied while offline.
+  // Determines if a request for |url| can be satisfied while offline.
   // This method always completes asynchronously.
   virtual void CanHandleMainResourceOffline(const GURL& url,
                                             const GURL& first_party,
@@ -84,6 +87,13 @@ class ServiceWorkerContext {
   virtual void GetAllOriginsInfo(const GetUsageInfoCallback& callback) = 0;
   virtual void DeleteForOrigin(const GURL& origin_url) = 0;
 
+  // Determines if |url| has a controlling Service Worker, and if that Service
+  // Worker also controls |other_url|.

[falken, 2015/02/05 10:26:11]

The language in the comment is a bit wrong, right now the function just checks
if there's a registration whose scope matches the URLs. "Controlling SW" implies
there's a ServiceWorkerVersion that is the .controller of an open page. This
should be something like "Determines if a Service Worker registration exists
that matches |url| and the same registration also matches |other_url|" and maybe
also "and has an active worker" depending on if you check .active().

[benwells, 2015/02/05 12:38:29]

Done.

+  virtual void CheckHasSameServiceWorker(
+      const GURL& url,
+      const GURL& other_url,
+      const CheckHasSameServiceWorkerCallback& callback) = 0;
+
  protected:
   ServiceWorkerContext() {}
   virtual ~ServiceWorkerContext() {}