Count exact cache size for time ranges

components/browsing_data/content/conditional_cache_counting_helper.h

Index: components/browsing_data/content/conditional_cache_counting_helper.h
diff --git a/components/browsing_data/content/conditional_cache_counting_helper.h b/components/browsing_data/content/conditional_cache_counting_helper.h
index d40fba6e20a5ef57fd7ae6f3aedb053ec80fe6b1..b5c6a8eb8f4334ba8a91f10890c6845a11f1e8a0 100644
--- a/components/browsing_data/content/conditional_cache_counting_helper.h
+++ b/components/browsing_data/content/conditional_cache_counting_helper.h
@@ -34,12 +34,17 @@ class ConditionalCacheCountingHelper {
 
   // Count the cache entries according to the specified time range. Destroys
   // this instance of ConditionalCacheCountingHelper when finished.
+  // The returned WeakPtr can be used to cancel the operation if necessary.
   // Must be called on the UI thread!
   //
   // The |completion_callback| will be invoked when the operation completes.
   base::WeakPtr<ConditionalCacheCountingHelper> CountAndDestroySelfWhenFinished(
       const CacheCountCallback& result_callback);
 
+  // Cancel the currently counting process. The task on the IO thread will stop
+  // and the callback will return net::ERR_ABORTED.
+  void CancelCounting();
+
   bool IsFinished();
 
  private:
@@ -66,6 +71,9 @@ class ConditionalCacheCountingHelper {
   void CountHttpCacheOnIOThread();
   void DoCountCache(int rv);
 
+  int CountEntries(disk_cache::Backend* backend);
+  void IterateOverEntries(int error);
+
   // 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.
@@ -75,6 +83,9 @@ class ConditionalCacheCountingHelper {
   const base::Time begin_time_;
   const base::Time end_time_;
 
+  // This flag is used to tell the IO thread to stop counting if the user
+  // called CancelCounting().
+  volatile bool is_cancelled_;
   bool is_finished_;
 
   const scoped_refptr<net::URLRequestContextGetter> main_context_getter_;
@@ -84,6 +95,7 @@ class ConditionalCacheCountingHelper {
   disk_cache::Backend* cache_;
 
   std::unique_ptr<disk_cache::Backend::Iterator> iterator_;
+  disk_cache::Entry* current_entry_;
 
   base::WeakPtrFactory<ConditionalCacheCountingHelper> weak_ptr_factory_;