Initial work to move downloads to ContentIds

components/offline_items_collection/core/offline_item.cc

Index: components/offline_items_collection/core/offline_item.cc
diff --git a/components/offline_items_collection/core/offline_item.cc b/components/offline_items_collection/core/offline_item.cc
index 81d47ea07d08fef31b693fd5285d5a10bc7ac188..4d4e03b8bc9a15f5869bccaca53b2732a095ff4a 100644
--- a/components/offline_items_collection/core/offline_item.cc
+++ b/components/offline_items_collection/core/offline_item.cc
@@ -11,7 +11,9 @@ ContentId::ContentId() = default;
 ContentId::ContentId(const ContentId& other) = default;
 
 ContentId::ContentId(const std::string& name_space, const std::string& id)
-    : name_space(name_space), id(id) {}
+    : name_space(name_space), id(id) {
+  DCHECK_EQ(std::string::npos, name_space.find_first_of(","));
+}
 
 ContentId::~ContentId() = default;