Push API: Don't require notification if tab is visible.

content/public/browser/push_messaging_service.h

Index: content/public/browser/push_messaging_service.h
diff --git a/content/public/browser/push_messaging_service.h b/content/public/browser/push_messaging_service.h
index 885cbc1d8e7a2d25620b3649d6484d0d751e9688..01248fe8ad9b11f4cb851b66dd1df4097eb873de 100644
--- a/content/public/browser/push_messaging_service.h
+++ b/content/public/browser/push_messaging_service.h
@@ -15,6 +15,8 @@
 
 namespace content {
 
+class WebContents;
+
 // A push service-agnostic interface that the Push API uses for talking to
 // push messaging services like GCM. Must only be used on the UI thread.
 class CONTENT_EXPORT PushMessagingService {
@@ -62,6 +64,9 @@ class CONTENT_EXPORT PushMessagingService {
   virtual blink::WebPushPermissionStatus GetPermissionStatus(
       const GURL& requesting_origin,
       const GURL& embedding_origin) = 0;
+
+ protected:
+  bool IsWebContentsUserVisible(const WebContents* web_contents);
 };
 
 }  // namespace content