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

chrome/browser/ui/tabs/tab_strip_model.cc

Index: chrome/browser/ui/tabs/tab_strip_model.cc
diff --git a/chrome/browser/ui/tabs/tab_strip_model.cc b/chrome/browser/ui/tabs/tab_strip_model.cc
index b7c60fbf90b974ee96176bae87dab73caad7e934..5d8e60dced924cd6c0857676644f8006d18c93b0 100644
--- a/chrome/browser/ui/tabs/tab_strip_model.cc
+++ b/chrome/browser/ui/tabs/tab_strip_model.cc
@@ -19,6 +19,7 @@
 #include "chrome/browser/ui/tab_contents/core_tab_helper_delegate.h"
 #include "chrome/browser/ui/tabs/tab_strip_model_delegate.h"
 #include "chrome/browser/ui/tabs/tab_strip_model_order_controller.h"
+#include "chrome/browser/ui/tabs/tab_utils.h"
 #include "chrome/browser/ui/web_contents_sizer.h"
 #include "chrome/common/url_constants.h"
 #include "components/web_modal/popup_manager.h"
@@ -701,6 +702,18 @@ bool TabStripModel::IsTabPinned(int index) const {
   return contents_data_[index]->pinned();
 }
 
+void TabStripModel::SetTabAudioMuted(int index, bool mute) {
+  content::WebContents* const contents = GetWebContentsAt(index);
+  if (!contents || !chrome::CanToggleAudioMute(contents))
+    return;
+  contents->SetAudioMuted(mute);
+}
+
+bool TabStripModel::IsTabAudioMuted(int index) const {
+  content::WebContents* const contents = GetWebContentsAt(index);
+  return contents && contents->IsAudioMuted();
+}
+
 bool TabStripModel::IsMiniTab(int index) const {
   return IsTabPinned(index) || IsAppTab(index);
 }
@@ -919,6 +932,18 @@ bool TabStripModel::IsContextMenuCommandEnabled(
       return false;
     }
 
+    case CommandToggleTabAudioMuted: {
+      if (!chrome::IsTabAudioMutingFeatureEnabled())
+        return false;
+      std::vector<int> indices = GetIndicesForCommand(context_index);
+      for (size_t i = 0; i < indices.size(); ++i) {
+        WebContents* const tab = GetWebContentsAt(indices[i]);
+        if (!tab || !chrome::CanToggleAudioMute(tab))
+          return false;
+      }
+      return true;
+    }
+
     case CommandBookmarkAllTabs:
       return browser_defaults::bookmarks_enabled &&
           delegate_->CanBookmarkAllTabs();
@@ -1026,6 +1051,18 @@ void TabStripModel::ExecuteContextMenuCommand(
       break;
     }
 
+    case CommandToggleTabAudioMuted: {
+      const bool mute = WillContextMenuMute(context_index);
+      if (mute)
+        content::RecordAction(UserMetricsAction("TabContextMenu_MuteTabs"));
+      else
+        content::RecordAction(UserMetricsAction("TabContextMenu_UnmuteTabs"));
+      std::vector<int> indices = GetIndicesForCommand(context_index);
+      for (size_t i = 0; i < indices.size(); ++i)
+        SetTabAudioMuted(indices[i], mute);
+      break;
+    }
+
     case CommandBookmarkAllTabs: {
       content::RecordAction(
           UserMetricsAction("TabContextMenu_BookmarkAllTabs"));
@@ -1091,6 +1128,16 @@ bool TabStripModel::WillContextMenuPin(int index) {
   return !all_pinned;
 }
 
+bool TabStripModel::WillContextMenuMute(int index) {
+  std::vector<int> indices = GetIndicesForCommand(index);
+  // If all tabs are muted, then we unmute, otherwise we mute.
+  for (size_t i = 0; i < indices.size(); ++i) {
+    if (!IsTabAudioMuted(indices[i]))
+      return true;
+  }
+  return false;
+}
+
 // static
 bool TabStripModel::ContextMenuCommandToBrowserCommand(int cmd_id,
                                                        int* browser_cmd) {