Add a size estimation mechanism to StoragePartitionHttpCacheDataRemover.

components/browsing_data/storage_partition_http_cache_data_remover.h

Index: components/browsing_data/storage_partition_http_cache_data_remover.h
diff --git a/components/browsing_data/storage_partition_http_cache_data_remover.h b/components/browsing_data/storage_partition_http_cache_data_remover.h
index eb9f575fae82478e918e5dd139d979ad09137f6b..40143e3b5abf75c40a3ba562c6e1a45e26012de9 100644
--- a/components/browsing_data/storage_partition_http_cache_data_remover.h
+++ b/components/browsing_data/storage_partition_http_cache_data_remover.h
@@ -8,6 +8,7 @@
 #include "base/callback.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "base/time/time.h"
+#include "net/base/completion_callback.h"
 
 namespace content {
 class StoragePartition;
@@ -34,13 +35,17 @@ class StoragePartitionHttpCacheDataRemover {
   // Calls |done_callback| upon completion and also destroys itself.
   void Remove(const base::Closure& done_callback);
 
+  // Counts the total size of entries that would be removed by calling |Remove|.
+  // Reports it via |result_callback| and then destroys itself.
+  void Count(const net::Int64CompletionCallback& result_callback);
+
  private:
   enum CacheState {
     STATE_NONE,
     STATE_CREATE_MAIN,
     STATE_CREATE_MEDIA,
-    STATE_DELETE_MAIN,
-    STATE_DELETE_MEDIA,
+    STATE_PROCESS_MAIN,
+    STATE_PROCESS_MEDIA,
     STATE_DONE
   };
 
@@ -58,9 +63,14 @@ class StoragePartitionHttpCacheDataRemover {
   ~StoragePartitionHttpCacheDataRemover();
 
   void ClearHttpCacheOnIOThread();
+  void CountHttpCacheOnIOThread();
+
   void ClearedHttpCache();
-  // Performs the actual work to delete the cache.
+  void CountedHttpCache();
+
+  // Performs the actual work to delete or count the cache.
   void DoClearCache(int rv);
+  void DoCountCache(int rv);
 
   const base::Time delete_begin_;
   const base::Time delete_end_;
@@ -69,11 +79,17 @@ class StoragePartitionHttpCacheDataRemover {
   const scoped_refptr<net::URLRequestContextGetter> media_context_getter_;
 
   base::Closure done_callback_;
+  net::Int64CompletionCallback result_callback_;
 
   // IO.
   int next_cache_state_;
   disk_cache::Backend* cache_;
 
+  // Stores the cache size computation result before it can be returned
+  // via a callback. This is either the sum of size of the the two cache
+  // backends, or an error code if the calculation failed.
+  int64 calculation_result_;
+
   DISALLOW_COPY_AND_ASSIGN(StoragePartitionHttpCacheDataRemover);
 };