Added AddDownload communication path and observers

components/offline_items_collection/core/offline_content_aggregator.cc

Index: components/offline_items_collection/core/offline_content_aggregator.cc
diff --git a/components/offline_items_collection/core/offline_content_aggregator.cc b/components/offline_items_collection/core/offline_content_aggregator.cc
index 19eaa574efe84bda5c98a87a569c7a2172fb004a..1ab86a3703e036c3c57329de6f069e69acf815f3 100644
--- a/components/offline_items_collection/core/offline_content_aggregator.cc
+++ b/components/offline_items_collection/core/offline_content_aggregator.cc
@@ -42,10 +42,14 @@ void OfflineContentAggregator::RegisterProvider(
 
   // Only set up the connection to the provider if the provider isn't associated
   // with any other namespace.
+  bool need_add_observer = false;

[David Trainor- moved to gerrit, 2017/04/25 03:24:43]

needs_add_observer = !MapContainsValue(providers_, provider_)?

   if (!MapContainsValue(providers_, provider))
-    provider->AddObserver(this);
+    need_add_observer = true;
 
   providers_[name_space] = provider;
+
+  if (need_add_observer)
+    provider->AddObserver(this);
 }
 
 void OfflineContentAggregator::UnregisterProvider(