SafeBrowsing: Track and cancel API checks.

components/safe_browsing_db/database_manager.h

Index: components/safe_browsing_db/database_manager.h
diff --git a/components/safe_browsing_db/database_manager.h b/components/safe_browsing_db/database_manager.h
index 62809a79882deeffc0b8956e3b489f155edacdd2..97a82014c2a8608db413204214c92fd1d1e0c75c 100644
--- a/components/safe_browsing_db/database_manager.h
+++ b/components/safe_browsing_db/database_manager.h
@@ -154,15 +154,19 @@ class SafeBrowsingDatabaseManager
   // are handled separately. To cancel an API check use CancelApiCheck.
   virtual void CancelCheck(Client* client) = 0;
 
-  // TODO(kcarattini): Add a CancelApiCheck method.
+  // Called on the IO thread to cancel a pending API check if the result is no
+  // longer needed. Returns true if the client was found and the check
+  // successfully cancelled.
+  virtual bool CancelApiCheck(Client* client);
 
   // Called on the IO thread to check if the given url has blacklisted APIs.
-  // "client" is called asynchronously with the result when it is ready.
-  // This method has the same implementation for both the local and remote
-  // database managers since it pings Safe Browsing servers directly without
-  // accessing the database at all.  Returns true if we can synchronously
-  // determine that the url is safe. Otherwise it returns false, and "client" is
-  // called asynchronously with the result when it is ready.
+  // "client" is called asynchronously with the result when it is ready. Callers
+  // should wait for results before calling this method a second time with the
+  // same client. This method has the same implementation for both the local and
+  // remote database managers since it pings Safe Browsing servers directly
+  // without accessing the database at all.  Returns true if we can
+  // synchronously determine that the url is safe. Otherwise it returns false,
+  // and "client" is called asynchronously with the result when it is ready.
   virtual bool CheckApiBlacklistUrl(const GURL& url, Client* client);
 
   // Called to initialize objects that are used on the io_thread, such as the
@@ -211,17 +215,29 @@ class SafeBrowsingDatabaseManager
                            HandleGetHashesWithApisResultsNoMatch);
   FRIEND_TEST_ALL_PREFIXES(SafeBrowsingDatabaseManagerTest,
                            HandleGetHashesWithApisResultsMatches);
+  FRIEND_TEST_ALL_PREFIXES(SafeBrowsingDatabaseManagerTest,
+                           CancelApiCheck);
+
+  typedef std::set<SafeBrowsingApiCheck*> CurrentApiChecks;
+
+  // In-progress checks. This set owns the SafeBrowsingApiCheck pointers and is
+  // responsible for deleting them when removing from the set.
+  CurrentApiChecks api_checks_;
 
   // Called on the IO thread wheh the SafeBrowsingProtocolManager has received
   // the full hash and api results for prefixes of the |url| argument in
   // CheckApiBlacklistUrl.
   virtual void HandleGetHashesWithApisResults(
-      std::shared_ptr<SafeBrowsingApiCheck> check,
+      SafeBrowsingApiCheck* check,
       const std::vector<SBFullHashResult>& full_hash_results,
       const base::TimeDelta& negative_cache_duration);
 
   // Created and destroyed via StartOnIOThread/StopOnIOThread.
   V4GetHashProtocolManager* v4_get_hash_protocol_manager_;
+
+ private:
+  // Returns an iterator to the pending API check with the given |client|.
+  CurrentApiChecks::iterator FindClientApiCheck(Client* client);
 };  // class SafeBrowsingDatabaseManager
 
 }  // namespace safe_browsing