[Sync] Componentize synced_tab_delegate

chrome/browser/supervised_user/supervised_user_navigation_observer.h

Index: chrome/browser/supervised_user/supervised_user_navigation_observer.h
diff --git a/chrome/browser/supervised_user/supervised_user_navigation_observer.h b/chrome/browser/supervised_user/supervised_user_navigation_observer.h
index 6149e616ce8ea4a58d99be63c1bf03d8f97e3c62..3400881f74a2a1d005bc02670da38ae1edceef4b 100644
--- a/chrome/browser/supervised_user/supervised_user_navigation_observer.h
+++ b/chrome/browser/supervised_user/supervised_user_navigation_observer.h
@@ -11,6 +11,7 @@
 #include "chrome/browser/supervised_user/supervised_user_service_observer.h"
 #include "chrome/browser/supervised_user/supervised_user_url_filter.h"
 #include "chrome/browser/supervised_user/supervised_users.h"
+#include "components/sessions/core/serialized_navigation_entry.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 class SupervisedUserService;
@@ -26,8 +27,8 @@ class SupervisedUserNavigationObserver
  public:
   ~SupervisedUserNavigationObserver() override;
 
-  const std::vector<const content::NavigationEntry*>*
-      blocked_navigations() const {
+  const std::vector<const sessions::SerializedNavigationEntry*>*
+  blocked_navigations() const {
     return &blocked_navigations_.get();
   }
 
@@ -63,7 +64,7 @@ class SupervisedUserNavigationObserver
   // Owned by SupervisedUserServiceFactory (lifetime of Profile).
   SupervisedUserService* supervised_user_service_;
 
-  ScopedVector<const content::NavigationEntry> blocked_navigations_;
+  ScopedVector<const sessions::SerializedNavigationEntry> blocked_navigations_;

[Bernhard Bauer, 2015/10/16 10:37:33]

If SerializedNavigationEntry is copyable (and we are okay with copying it
around), we could also make this a plain std::vector.

[Nicolas Zea, 2015/10/20 23:14:41]

It is copyable, but that could be fairly expensive, so I think I'd prefer to
leave it like this.

[Bernhard Bauer, 2015/10/21 10:48:34]

Hm, in that case...
1. Wouldn't it make sense to move the newly allocated SerializedNavigationEntry
in there instead of copying it?
2. In general, I find that if it is possible to use something in the wrong way,
people will do it. So if copying is indeed expensive, should we disallow
implicit copying and assignment, and maybe add an explicit Copy() method?

[Nicolas Zea, 2015/10/22 00:29:11]

It's not so much that making copies is bad, as that Session sync will be
accessing this theoretically quite often.

Keep in mind, we only make a new copy when we create the serialized navigation
entry, which in this case is whenever a new navigation is blocked, so should be
fairly rare.

On the other hand, Sessions sync will be accessing the set of blocked
navigations at least as often as on every navigation within that tab. That's
much more common, and is the scenario I'd prefer to avoid doing unnecessary
copying with.

 
   base::WeakPtrFactory<SupervisedUserNavigationObserver> weak_ptr_factory_;