libloc_api: xtra injection improvements

* Hold the locks only for copying buffer data to reduce the wait time
  for xtra injection.
* Remove some incorrect locks while doing deferred xtra injection.
* Switch to buffering the injection if the engine is on, as doing so
  now functions as intended.

Change-Id: I1b75945907242e960ce4b275f10b7f9f8dc17606

loc_api/libloc_api/loc_eng.cpp

@@ -2190,11 +2190,7 @@ static void loc_eng_deferred_action_thread(void* arg)
       if (loc_eng_data.engine_status != GPS_STATUS_ENGINE_ON &&
           loc_eng_data.xtra_module_data.xtra_data_for_injection != NULL)
       {
-         pthread_mutex_unlock(&loc_eng_data.deferred_action_mutex);
-
          loc_eng_inject_xtra_data_in_buffer();
-
-         pthread_mutex_lock(&loc_eng_data.deferred_action_mutex);
       }
 
       //Process connectivity manager events at this point

loc_api/libloc_api/loc_eng_xtra.cpp

@@ -60,8 +60,8 @@ const GpsXtraInterface sLocEngXTRAInterface =
 {
     sizeof(GpsXtraInterface),
     qct_loc_eng_xtra_init,
-    qct_loc_eng_inject_xtra_data,
-    /* qct_loc_eng_inject_xtra_data_proxy, */ // This func buffers xtra data if GPS is in-session
+    /* qct_loc_eng_inject_xtra_data, */
+    qct_loc_eng_inject_xtra_data_proxy, // This func buffers xtra data if GPS is in-session
 };
 
 /*===========================================================================
@@ -215,28 +215,31 @@ SIDE EFFECTS
 int loc_eng_inject_xtra_data_in_buffer()
 {
    int rc = 0;
+   char *data;
+   int length;
 
    pthread_mutex_lock(&loc_eng_data.xtra_module_data.lock);
 
-   if (loc_eng_data.xtra_module_data.xtra_data_for_injection)
+   data = loc_eng_data.xtra_module_data.xtra_data_for_injection;
+   length = loc_eng_data.xtra_module_data.xtra_data_len;
+
+   loc_eng_data.xtra_module_data.xtra_data_for_injection = NULL;
+   loc_eng_data.xtra_module_data.xtra_data_len = 0;
+
+   pthread_mutex_unlock(&loc_eng_data.xtra_module_data.lock);
+
+   if (data)
    {
-      if (qct_loc_eng_inject_xtra_data(
-            loc_eng_data.xtra_module_data.xtra_data_for_injection,
-            loc_eng_data.xtra_module_data.xtra_data_len))
+      if (qct_loc_eng_inject_xtra_data(data, length))
       {
          // FIXME gracefully handle injection error
          LOC_LOGE("XTRA injection failed.");
          rc = -1;
       }
 
-      // Clears buffered data
-      free(loc_eng_data.xtra_module_data.xtra_data_for_injection);
-      loc_eng_data.xtra_module_data.xtra_data_for_injection = NULL;
-      loc_eng_data.xtra_module_data.xtra_data_len = 0;
+      free(data);
    }
 
-   pthread_mutex_unlock(&loc_eng_data.xtra_module_data.lock);
-
    return rc;
 }