SL-3704 Give plugins some time to terminate

requestExit() doesn't close CEF, command sets CEF into closing state which will be processed on update()

indra/llplugin/llpluginprocesschild.cpp

@@ -225,6 +225,18 @@ void LLPluginProcessChild::idle(void)
 				}
 				setState(STATE_UNLOADED);
 			}
+
+            if (mInstance)
+            {
+                // Provide some time to the plugin
+                // example: CEF on "cleanup" sets shutdown request, but it still needs idle loop to actually shutdown
+                LLPluginMessage message("base", "idle");
+                message.setValueReal("time", PLUGIN_IDLE_SECONDS);
+                sendMessageToPlugin(message);
+
+                mInstance->idle();
+            }
+
 			break;
 
 		case STATE_UNLOADED:

indra/media_plugins/cef/media_plugin_cef.cpp

@@ -460,7 +460,6 @@ void MediaPluginCEF::receiveMessage(const char* message_string)
 			}
 			else if (message_name == "cleanup")
 			{
-				mVolumeCatcher.setVolume(0); // Hack: masks CEF exit issues
 				mCEFLib->requestExit();
 			}
 			else if (message_name == "force_exit")