Continue to process AnalyserNode if inputs are silent.

third_party/WebKit/Source/modules/webaudio/AudioBasicInspectorNode.cpp

 /*
  * Copyright (C) 2012, Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 97 matching lines @@
       m_needAutomaticPull = false;
     }
   } else {
     unsigned numberOfInputConnections = input(0).numberOfRenderingConnections();
     if (numberOfInputConnections && !m_needAutomaticPull) {
       // When an AudioBasicInspectorNode is not connected to any downstream node
       // while still connected from upstream node(s), add it to the context's
       // automatic pull list.
       context()->deferredTaskHandler().addAutomaticPullNode(this);
       m_needAutomaticPull = true;
-    } else if (!numberOfInputConnections && m_needAutomaticPull) {
-      // The AudioBasicInspectorNode is connected to nothing, remove it from the
-      // context's automatic pull list.
+    } else if (!numberOfInputConnections && m_needAutomaticPull &&
+               getNodeType() != NodeTypeAnalyser) {
+      // The AudioBasicInspectorNode is connected to nothing and is
+      // not an AnalyserNode, remove it from the context's automatic
+      // pull list.  AnalyserNode's need to be pulled even with no
+      // inputs so that the internal state gets updated to hold the
+      // right time and FFT data.

[hongchan, 2017/02/01 01:12:11]

We should at least consider refactoring this method; we can extract the common
part to the parent class, and leave the detail in the derived one. Not an easy
task, but we should try.

[Raymond Toy, 2017/02/01 21:21:01]

Done.  But a bit of duplication.

       context()->deferredTaskHandler().removeAutomaticPullNode(this);
       m_needAutomaticPull = false;
     }
   }
 }
 
 }  // namespace blink