media: Use fake audio manager in headless mode

media/audio/linux/audio_manager_linux.cc

 // Copyright (c) 2012 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 "base/command_line.h"
 #include "base/metrics/histogram.h"
+#include "media/audio/fake_audio_manager.h"
 #include "media/base/media_switches.h"
+#include "ui/gfx/switches.h"
 
 #if defined(USE_ALSA)
 #include "media/audio/alsa/audio_manager_alsa.h"
-#else
-#include "media/audio/fake_audio_manager.h"
 #endif
 #if defined(USE_CRAS)
 #include "media/audio/cras/audio_manager_cras.h"
 #endif
 #if defined(USE_PULSEAUDIO)
 #include "media/audio/pulse/audio_manager_pulse.h"
 #endif
 
 namespace media {
 
 enum LinuxAudioIO {
   kPulse,
   kAlsa,
   kCras,
   kAudioIOMax = kCras  // Must always be equal to largest logged entry.
 };
 
 ScopedAudioManagerPtr CreateAudioManager(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
     AudioLogFactory* audio_log_factory) {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kHeadless)) {

[tommi (sloooow) - chröme, 2017/01/13 18:02:27]

This is bringing in unit test code into production code.  Instead, we should
just use the ForTesting factory methods in tests that require it.  As is, this
would change all tests running in headless mode to use the FakeAudioManager and
we'd lose testing of the actual code that works with the audio hardware.

[Sami, 2017/01/13 18:38:06]

Sorry, which tests are you referring to? The --headless switch is used by Chrome
users who wish to run the browser in headless mode for automation purposes. Is
there another way we could avoid requiring audio hardware in such a setup (e.g.,
a server environment)?

[Sami, 2017/01/13 18:51:04]

FWIW there's some more background about Headless Chrome here:
https://chromium.googlesource.com/chromium/src/+/master/headless/README.md

+    return ScopedAudioManagerPtr(
+        new FakeAudioManager(std::move(task_runner),
+                             std::move(worker_task_runner), audio_log_factory));
+  }
+
 #if defined(USE_CRAS)
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kUseCras)) {
     UMA_HISTOGRAM_ENUMERATION("Media.LinuxAudioIO", kCras, kAudioIOMax + 1);
     return ScopedAudioManagerPtr(
         new AudioManagerCras(std::move(task_runner),
                              std::move(worker_task_runner), audio_log_factory));
   }
 #endif
 
 #if defined(USE_PULSEAUDIO)
@@ skipping 16 matching lines @@
       new AudioManagerAlsa(std::move(task_runner),
                            std::move(worker_task_runner), audio_log_factory));
 #else
   return ScopedAudioManagerPtr(
       new FakeAudioManager(std::move(task_runner),
                            std::move(worker_task_runner), audio_log_factory));
 #endif
 }
 
 }  // namespace media