Updated audio quality test comments; win7 instructions were wrong.

chrome/browser/media/webrtc/webrtc_audio_quality_browsertest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 
 #include <ctime>
 
 #include "base/command_line.h"
 #include "base/files/file_enumerator.h"
@@ skipping 101 matching lines @@
 // 7. Try launching chrome as the target user on the target machine, try
 //    playing, say, a YouTube video, and record with 'rec test.wav trim 0 5'.
 //    Stop the video in chrome and try playing back the file; you should hear
 //    a recording of the video (note; if you play back on the target machine
 //    you must revert the changes in step 3 first).
 //
 // On Windows 7:
 // 1. Control panel > Sound > Manage audio devices.
 // 2. In the recording tab, right-click in an empty space in the pane with the
 //    devices. Tick 'show disabled devices'.
-// 3. You should see a 'stero mix' device - this is what your speakers output.
+// 3. You should see a 'stereo mix' device - this is what your speakers output.
+//    If you don't have one, your driver doesn't support stereo mix devices.
+//    Some drivers use different names for the mix device though (like "Wave").
 //    Right click > Properties.
-// 4. In the Listen tab for the mix device, check the 'listen to this device'
-//    checkbox. Ensure the mix device is the default recording device.
-// 5. Launch chrome and try playing a video with sound. You should see
+// 4. Ensure "listen to this device" is unchecked, otherwise you get echo.
+// 5. Ensure the mix device is the default recording device.
+// 6. Launch chrome and try playing a video with sound. You should see
 //    in the volume meter for the mix device. Configure the mix device to have
 //    50 / 100 in level. Also go into the playback tab, right-click Speakers,
 //    and set that level to 50 / 100. Otherwise you will get distortion in
 //    the recording.
 class MAYBE_WebRtcAudioQualityBrowserTest : public WebRtcTestBase {
  public:
   MAYBE_WebRtcAudioQualityBrowserTest() {}
   void SetUpInProcessBrowserTestFixture() override {
     DetectErrorsInJavaScript();  // Look for errors in our rather complex js.
   }
@@ skipping 677 matching lines @@
     MANUAL_TestAutoGainIsOffWithAudioProcessingOff
 #endif
 // Since the AGC is off here there should be no gain at all.
 IN_PROC_BROWSER_TEST_F(MAYBE_WebRtcAudioQualityBrowserTest,
                        MAYBE_MANUAL_TestAutoGainIsOffWithAudioProcessingOff) {
   const char* kAudioCallWithoutAudioProcessing =
       "{audio: { mandatory: { echoCancellation: false } } }";
   ASSERT_NO_FATAL_FAILURE(TestAutoGainControl(
       kReferenceFile, kAudioCallWithoutAudioProcessing, "_no_agc"));
 }