bgsave: various documentation cleanups & a missing const.

Signed-off-by: Michael Meeks <michael.meeks@collabora.com>
Change-Id: I55636718815adc1b294219304e7fd060f88f9c15

common/MessageQueue.hpp

@@ -77,7 +77,7 @@ public:
         return _queue.empty();
     }
 
-    size_t size()
+    size_t size() const
     {
         return _queue.size();
     }

kit/ChildSession.cpp

@@ -879,8 +879,9 @@ bool ChildSession::saveDocumentBackground(const StringVector &tokens)
         sendTextFrame("asyncsave end");
 
         LOG_TRC("Finished synchronous background saving ...");
-        // Now we wait for an async UNO_COMMAND_RESULT on .uno:Save
-    }, getViewId())) // FIXME: shared_from_this surely ?
+        // Next: we wait for an async UNO_COMMAND_RESULT on .uno:Save
+        // cf. Document::handleSaveMessage.
+    }, getViewId()))
         return false; // fork failed
 
     LOG_TRC("saveDocumentBackground returns succesful start.");

kit/Kit.cpp

@@ -1339,6 +1339,9 @@ void Document::handleSaveMessage(const std::string &)
 
             // We don't want to wait around for the parent's websocket
             socket->shutdownAfterWriting();
+
+            // This means we don't get to send statechanged: .uno:ModifiedStatus
+            // which is fine - we want to leave that to the Kit process.
         }
         else
             LOG_TRC("Shutting down already shutdown bgsv child's socket to parent kit post save");
@@ -2087,6 +2090,8 @@ bool Document::isTileRequestInsideVisibleArea(const TileCombined& tileCombined)
 // poll is idle, are we ?
 void Document::checkIdle()
 {
+    // FIXME: can have Idle CallbackFlushHandler work in the core.
+
     if (!processInputEnabled() || hasQueueItems())
     {
         LOG_TRC("Nearly idle - but have more queued items to process");