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

chrome/browser/ui/views/tabs/tab_strip.cc

Index: chrome/browser/ui/views/tabs/tab_strip.cc
diff --git a/chrome/browser/ui/views/tabs/tab_strip.cc b/chrome/browser/ui/views/tabs/tab_strip.cc
index d6abe35f73b5de5b3ff3d3bcdd7d687d691f0102..7513fd558bdfb40694b4f764ff673f3be779befa 100644
--- a/chrome/browser/ui/views/tabs/tab_strip.cc
+++ b/chrome/browser/ui/views/tabs/tab_strip.cc
@@ -1004,6 +1004,12 @@ void TabStrip::CloseTab(Tab* tab, CloseTabSource source) {
     controller_->CloseTab(model_index, source);
 }
 
+void TabStrip::ToggleTabAudioMute(Tab* tab) {
+  int model_index = GetModelIndexOfTab(tab);
+  if (IsValidModelIndex(model_index))
+    controller_->ToggleTabAudioMute(model_index);
+}
+
 void TabStrip::ShowContextMenuForTab(Tab* tab,
                                      const gfx::Point& p,
                                      ui::MenuSourceType source_type) {