Hotword: Fix always-on case by removing MS_CONFIGURED timeout

chrome/browser/resources/hotword/nacl_manager.js

Index: chrome/browser/resources/hotword/nacl_manager.js
diff --git a/chrome/browser/resources/hotword/nacl_manager.js b/chrome/browser/resources/hotword/nacl_manager.js
index 4b10183b5eb519df1ee77745c7f229515772b0bb..e4279284ad1b48611610b8300bd2b49bf5bf489d 100644
--- a/chrome/browser/resources/hotword/nacl_manager.js
+++ b/chrome/browser/resources/hotword/nacl_manager.js
@@ -460,8 +460,13 @@ NaClManager.prototype.handleModelLoaded_ = function() {
     return;
   }
   this.sendDataToPlugin_(this.stream_.getAudioTracks()[0]);
-  this.waitForMessage_(hotword.constants.TimeoutMs.LONG,
-                       hotword.constants.NaClPlugin.MS_CONFIGURED);
+  // The plugin will send a MS_CONFIGURED, but don't set a timeout waiting for
+  // it. After the recent MediaStreamAudioTrack refactoring, the behavior of

[Matt Giuca, 2016/09/08 03:50:45]

The code should describe what it is *now*, not refer to what it was (which will
become less and less relevant as time goes on). Especially avoid time-sensitive
terms like "recent".

It would be good to move the discussion of recent changes to the commit log
rather than the code.

For the code comments, how about:
"The plugin will send a MS_CONFIGURED, but don't set a timeout waiting for it.
MediaStreamAudioTrack::Configure() will remain pending until the first audio
buffer is received. When the audio source is a DSP for always-on detection, no
audio sample is sent until the DSP detects a potential hotword trigger. Thus,
Configure would remain pending indefinitely if we were to wait here. See
https://crbug.com/616203."

(Note also: I added "https://" to the URL so it is clickable in some editors.)

+  // MediaStreamAudioTrack::Configure() changed where it remains pending until
+  // the first audio buffer is received. When the audio source is a DSP for
+  // always-on detection, no audio sample is sent until the DSP detects a
+  // potential hotword trigger. Thus, Configure may remain pending indefinitely.
+  // See crbug.com/616203 for more info.
 };
 
 /**