mash: Use ChromeLauncherControllerImpl, remove Mus subclass stub.

chrome/browser/ui/ash/launcher/browser_status_monitor.cc

Index: chrome/browser/ui/ash/launcher/browser_status_monitor.cc
diff --git a/chrome/browser/ui/ash/launcher/browser_status_monitor.cc b/chrome/browser/ui/ash/launcher/browser_status_monitor.cc
index 56d1117197caa85f2dc0b23dc86a4d4fa181eccc..49c615b92069bce48e3f51458c461d6ef04b1ea6 100644
--- a/chrome/browser/ui/ash/launcher/browser_status_monitor.cc
+++ b/chrome/browser/ui/ash/launcher/browser_status_monitor.cc
@@ -8,6 +8,7 @@
 #include "ash/wm/window_util.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "chrome/browser/ui/ash/ash_util.h"
 #include "chrome/browser/ui/ash/launcher/browser_shortcut_launcher_item_controller.h"
 #include "chrome/browser/ui/ash/launcher/chrome_launcher_controller.h"
 #include "chrome/browser/ui/ash/launcher/chrome_launcher_controller_util.h"
@@ -82,11 +83,14 @@ BrowserStatusMonitor::BrowserStatusMonitor(
     : launcher_controller_(launcher_controller),
       browser_tab_strip_tracker_(this, this, this) {
   DCHECK(launcher_controller_);
-  ash::Shell::Get()->activation_client()->AddObserver(this);
+  // TODO(crbug.com/557406): Fix this interaction pattern in Mash.
+  if (!ash_util::IsRunningInMash())
+    ash::Shell::Get()->activation_client()->AddObserver(this);
 }
 
 BrowserStatusMonitor::~BrowserStatusMonitor() {
-  ash::Shell::Get()->activation_client()->RemoveObserver(this);
+  if (!ash_util::IsRunningInMash())
+    ash::Shell::Get()->activation_client()->RemoveObserver(this);
   browser_tab_strip_tracker_.StopObservingAndSendOnBrowserRemoved();
 }