Make tab audible and muted states and cause available for an extension API

chrome/browser/ui/tabs/tab_strip_model_observer.cc

Index: chrome/browser/ui/tabs/tab_strip_model_observer.cc
diff --git a/chrome/browser/ui/tabs/tab_strip_model_observer.cc b/chrome/browser/ui/tabs/tab_strip_model_observer.cc
index 6b3911b0b184e93083a889eb29b35c8d88703f8e..08c5d2a39ae7c1fbe33e4670154da8e8154fb9d6 100644
--- a/chrome/browser/ui/tabs/tab_strip_model_observer.cc
+++ b/chrome/browser/ui/tabs/tab_strip_model_observer.cc
@@ -54,6 +54,15 @@ void TabStripModelObserver::TabPinnedStateChanged(WebContents* contents,
                                                   int index) {
 }
 
+void TabStripModelObserver::TabAudibleStateChanged(WebContents* contents,
+                                                   bool audible) {
+}
+
+void TabStripModelObserver::TabMutedStateChanged(WebContents* contents,
+                                                 bool muted,
+                                                 const std::string& cause) {
+}
+
 void TabStripModelObserver::TabMiniStateChanged(WebContents* contents,
                                                 int index) {
 }