Make BrowserList::(Add|Remove)Observer add the observer to every desktop's browser list.

chrome/browser/automation/testing_automation_provider.cc

Index: chrome/browser/automation/testing_automation_provider.cc
diff --git a/chrome/browser/automation/testing_automation_provider.cc b/chrome/browser/automation/testing_automation_provider.cc
index fe99a4cf698436ce627f710e5dc5c52ccdc20f8b..2ad5160848cc6af8d0813200b311074ba060963f 100644
--- a/chrome/browser/automation/testing_automation_provider.cc
+++ b/chrome/browser/automation/testing_automation_provider.cc
@@ -93,6 +93,7 @@
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_instant_controller.h"
 #include "chrome/browser/ui/browser_iterator.h"
+#include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/browser_list_impl.h"
 #include "chrome/browser/ui/browser_tabstrip.h"
 #include "chrome/browser/ui/browser_window.h"
@@ -254,9 +255,7 @@ TestingAutomationProvider::TestingAutomationProvider(Profile* profile)
       , power_manager_observer_(NULL)
 #endif
       {
-  // The automation layer doesn't support non-native desktops.
-  chrome::BrowserListImpl::GetInstance(
-      chrome::HOST_DESKTOP_TYPE_NATIVE)->AddObserver(this);
+  BrowserList::AddObserver(this);
   registrar_.Add(this, chrome::NOTIFICATION_SESSION_END,
                  content::NotificationService::AllSources());
 #if defined(OS_CHROMEOS)
@@ -268,9 +267,7 @@ TestingAutomationProvider::~TestingAutomationProvider() {
 #if defined(OS_CHROMEOS)
   RemoveChromeosObservers();
 #endif
-  // The automation layer doesn't support non-native desktops.
-  chrome::BrowserListImpl::GetInstance(
-      chrome::HOST_DESKTOP_TYPE_NATIVE)->RemoveObserver(this);
+  BrowserList::RemoveObserver(this);
 }
 
 IPC::Channel::Mode TestingAutomationProvider::GetChannelMode(