Tab audio mute control (views UI), behind a switch (off by default).

chrome/browser/about_flags.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 "chrome/browser/about_flags.h"
 
 #include <iterator>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 1908 matching lines @@
   },
 #endif  // OS_CHROMEOS
   {
     "enable-data-reduction-proxy-alt",
     IDS_FLAGS_ENABLE_DATA_REDUCTION_PROXY_ALTERNATIVE_NAME,
     IDS_FLAGS_ENABLE_DATA_REDUCTION_PROXY_ALTERNATIVE_DESCRIPTION,
     kOsAndroid,
     SINGLE_VALUE_TYPE(data_reduction_proxy::switches::
                           kEnableDataReductionProxyAlt)
   },
+#if defined(USE_AURA)
+  {
+    "enable-tab-audio-muting",
+    IDS_FLAGS_ENABLE_TAB_AUDIO_MUTING_NAME,
+    IDS_FLAGS_ENABLE_TAB_AUDIO_MUTING_DESCRIPTION,
+    kOsWin | kOsLinux | kOsCrOS,
+    SINGLE_VALUE_TYPE(switches::kEnableTabAudioMuting)
+  },
+#endif  // defined(USE_AURA)
 
   // NOTE: Adding new command-line switches requires adding corresponding
   // entries to enum "LoginCustomFlags" in histograms.xml. See note in
   // histograms.xml and don't forget to run AboutFlagsHistogramTest unit test.
 };
 
 const Experiment* experiments = kExperiments;
 size_t num_experiments = arraysize(kExperiments);
 
 // Stores and encapsulates the little state that about:flags has.
@@ skipping 571 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags