NetServices: Implement BHttpSession::Cancel()

Change-Id: Iff0a7726e57f3e6bd4e9d0ebac08a370d25a62d7

docs/user/netservices/HttpSession.dox

@@ -183,6 +183,42 @@ namespace Network {
 */
 
 
+/*!
+	\fn void BHttpSession::Cancel(int32 identifier)
+	\brief Cancel a running request.
+
+	When a request that is scheduled or running is cancelled, its \ref BHttpResult object will
+	be set to the \ref BNetworkRequestError exception with the \c Cancelled type.
+
+	There are three possible outcomes:
+	1. If the request is not yet scheduled, then it will never start. The result will be set to
+		the cancelled error state.
+	2. If the request was started, then processing it will be terminated. The result will be set to
+		the cancelled error state.
+	3. If the request was already finished, then nothing happens. The result will keep the value it
+		had assigned. The same if the request identifier is invalid.
+
+	\param identifier The identifier for the request to cancel.
+
+	\exception std::bad_alloc Error in case memory cannot be allocated.
+
+	\since Haiku R1
+*/
+
+
+/*!
+	\fn void BHttpSession::Cancel(const BHttpResult& request)
+	\brief Cancel a running \a request.
+
+	See the \ref BHttpSession::Cancel(int32 identifier) method for more details on how this method
+	works.
+
+	\exception std::bad_alloc Error in case memory cannot be allocated.
+
+	\since Haiku R1
+*/
+
+
 } // namespace Network
 
 } // namespace BPrivate