[Offline pages] Moving disk size related calls to Archive Manager, reorganizing UMA

components/offline_pages/archive_manager.h

Index: components/offline_pages/archive_manager.h
diff --git a/components/offline_pages/archive_manager.h b/components/offline_pages/archive_manager.h
index 6441d85fdc82ffe85c3641bd0e1037883d728bbf..c81499ee23e87b7423400f6c1bdfd6486bd6b45f 100644
--- a/components/offline_pages/archive_manager.h
+++ b/components/offline_pages/archive_manager.h
@@ -23,6 +23,11 @@ namespace offline_pages {
 // All tasks are performed using |task_runner_|.
 class ArchiveManager {
  public:
+  struct StorageStats {
+    int64_t free_disk_space;
+    int64_t total_archives_size;
+  };
+
   ArchiveManager(const base::FilePath& archives_dir,
                  const scoped_refptr<base::SequencedTaskRunner>& task_runner);
   virtual ~ArchiveManager();
@@ -52,6 +57,12 @@ class ArchiveManager {
       const base::Callback<void(const std::set<base::FilePath>&)>& callback)
       const;
 
+  // Gets stats about archive storage, i.e. total archive sizes and free disk
+  // space.
+  virtual void GetStorageStats(
+      const base::Callback<void(const StorageStats& storage_sizes)>& callback)
+      const;
+
  private:
   // Path under which all of the managed archives should be stored.
   base::FilePath archives_dir_;