[SYCL] Fix queue command_graph namespace

- Remove sycl:: from command_graph namespace in queue
- Improve comments

Author: Bensuo

sycl/include/sycl/queue.hpp

@@ -1085,18 +1085,22 @@ class __SYCL_EXPORT queue {
 
 public:
   /// Places the queue into command_graph recording mode.
-  /// Returns true if the queue was not already in recording mode.
-  bool begin_recording(
-      sycl::ext::oneapi::experimental::command_graph<
-          sycl::ext::oneapi::experimental::graph_state::modifiable> &graph);
+  ///
+  /// \return true if the queue was not already in recording mode.
+  bool
+  begin_recording(ext::oneapi::experimental::command_graph<
+                  ext::oneapi::experimental::graph_state::modifiable> &graph);
 
   /// Ends recording mode on the queue and returns to the normal state.
-  /// Returns true if the queue was already in recording mode.
+  ///
+  /// \return true if the queue was already in recording mode.
   bool end_recording();
 
   /// Submits an executable command_graph for execution on this queue
-  event submit(sycl::ext::oneapi::experimental::command_graph<
-               sycl::ext::oneapi::experimental::graph_state::executable>
+  ///
+  /// \return an event representing the execution of the command_graph
+  event submit(ext::oneapi::experimental::command_graph<
+               ext::oneapi::experimental::graph_state::executable>
                    graph);
 
 private:

sycl/source/queue.cpp

@@ -216,8 +216,8 @@ bool queue::device_has(aspect Aspect) const {
 }
 
 bool begin_recording(
-    sycl::ext::oneapi::experimental::command_graph<
-        sycl::ext::oneapi::experimental::graph_state::modifiable> &graph) {
+    ext::oneapi::experimental::command_graph<
+        ext::oneapi::experimental::graph_state::modifiable> &graph) {
   // Empty Implementation
   return true;
 }
@@ -227,10 +227,11 @@ bool end_recording() {
   return true;
 }
 
-event submit(sycl::ext::oneapi::experimental::command_graph<
-             sycl::ext::oneapi::experimental::graph_state::executable>
+event submit(ext::oneapi::experimental::command_graph<
+             ext::oneapi::experimental::graph_state::executable>
                  graph) {
-  return sycl::event{};
+  // Empty implementation
+  return {};
 }
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl