[Offline Pages] Linking storage manager and model with UMAs.

components/offline_pages/offline_page_model.h

Index: components/offline_pages/offline_page_model.h
diff --git a/components/offline_pages/offline_page_model.h b/components/offline_pages/offline_page_model.h
index 03aba53e238e2e1a87e6c0166cca27c268e70f04..df79989d2bfde31ea4d0d816635a4fdf1a8de2ed 100644
--- a/components/offline_pages/offline_page_model.h
+++ b/components/offline_pages/offline_page_model.h
@@ -340,6 +340,16 @@ class OfflinePageModel : public KeyedService,
                         const base::Time& expiration_time,
                         bool success);
 
+  // Calls storage manager to clear expired pages if there's any. Used to

[jianli, 2016/05/27 19:16:13]

nit: you don't need to explain the implementation details in the function
comment. Probably just enough to say:
  // Clears expired pages if there are any.

[romax, 2016/05/27 20:36:02]

Done.

+  // invoke ClearPagesIfNeeded on storage manager to clear storage
+  // 'automatically'.
+  void ClearStorageIfNeeded(
+      const OfflinePageStorageManager::ClearStorageCallback& callback);
+
+  // Callback completing storage clearing/

[jianli, 2016/05/27 19:16:13]

nit: / => .

[romax, 2016/05/27 20:36:02]

Done.

+  void OnStorageCleared(const size_t expired_page_count,
+                        OfflinePageStorageManager::ClearStorageResult result);
+
   void RunWhenLoaded(const base::Closure& job);
 
   // Persistent store for offline page metadata.