Creates BrowserTabStripTracker to consolidate common code

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 31cffa66c0eb4fb5d422bfee11d9cbfbe53e495a..a3eb0435416e6a0ba7b8102f04b0077eb4c87c1d 100644
--- a/chrome/browser/ui/ash/launcher/browser_status_monitor.cc
+++ b/chrome/browser/ui/ash/launcher/browser_status_monitor.cc
@@ -104,9 +104,10 @@ BrowserStatusMonitor::BrowserStatusMonitor(
     : launcher_controller_(launcher_controller),
       observed_activation_clients_(this),
       observed_root_windows_(this),
-      settings_window_observer_(new SettingsWindowObserver) {
+      settings_window_observer_(new SettingsWindowObserver),
+      browser_tab_strip_tracker_(this, this, this) {
   DCHECK(launcher_controller_);
-  BrowserList::AddObserver(this);
+
   chrome::SettingsWindowManager::GetInstance()->AddObserver(
       settings_window_observer_.get());
 
@@ -127,6 +128,9 @@ BrowserStatusMonitor::BrowserStatusMonitor(
     }
     ash::Shell::GetInstance()->GetScreen()->AddObserver(this);
   }
+
+  browser_tab_strip_tracker_.Init(
+      BrowserTabStripTracker::InitWith::ALL_BROWERS);
 }
 
 BrowserStatusMonitor::~BrowserStatusMonitor() {
@@ -138,14 +142,7 @@ BrowserStatusMonitor::~BrowserStatusMonitor() {
   chrome::SettingsWindowManager::GetInstance()->RemoveObserver(
       settings_window_observer_.get());
 
-  BrowserList::RemoveObserver(this);
-
-  BrowserList* browser_list =
-      BrowserList::GetInstance(chrome::HOST_DESKTOP_TYPE_ASH);
-  for (BrowserList::const_iterator i = browser_list->begin();
-       i != browser_list->end(); ++i) {
-    OnBrowserRemoved(*i);
-  }
+  browser_tab_strip_tracker_.StopObservingAndSendOnBrowserRemoved();
 
   STLDeleteContainerPairSecondPointers(webcontents_to_observer_map_.begin(),
                                        webcontents_to_observer_map_.end());
@@ -211,28 +208,22 @@ void BrowserStatusMonitor::OnWindowDestroyed(aura::Window* window) {
       aura::client::GetActivationClient(window));
 }
 
-void BrowserStatusMonitor::OnBrowserAdded(Browser* browser) {
-  if (browser->host_desktop_type() != chrome::HOST_DESKTOP_TYPE_ASH)
-    return;
+bool BrowserStatusMonitor::ShouldTrackBrowser(Browser* browser) {
+  return browser->host_desktop_type() == chrome::HOST_DESKTOP_TYPE_ASH;
+}
 
+void BrowserStatusMonitor::OnBrowserAdded(Browser* browser) {
   if (browser->is_type_popup() && browser->is_app()) {
     // Note: A V1 application will set the tab strip observer when the app gets
     // added to the shelf. This makes sure that in the multi user case we will
     // only set the observer while the app item exists in the shelf.
     AddV1AppToShelf(browser);
-  } else {
-    browser->tab_strip_model()->AddObserver(this);
   }
 }
 
 void BrowserStatusMonitor::OnBrowserRemoved(Browser* browser) {
-  if (browser->host_desktop_type() != chrome::HOST_DESKTOP_TYPE_ASH)
-    return;
-
   if (browser->is_type_popup() && browser->is_app())
     RemoveV1AppFromShelf(browser);
-  else
-    browser->tab_strip_model()->RemoveObserver(this);
 
   UpdateBrowserItemState();
 }
@@ -349,8 +340,6 @@ void BrowserStatusMonitor::WebContentsDestroyed(
 void BrowserStatusMonitor::AddV1AppToShelf(Browser* browser) {
   DCHECK(browser->is_type_popup() && browser->is_app());
 
-  browser->tab_strip_model()->AddObserver(this);
-
   std::string app_id =
       web_app::GetExtensionIdFromApplicationName(browser->app_name());
   if (!app_id.empty()) {
@@ -362,8 +351,6 @@ void BrowserStatusMonitor::AddV1AppToShelf(Browser* browser) {
 void BrowserStatusMonitor::RemoveV1AppFromShelf(Browser* browser) {
   DCHECK(browser->is_type_popup() && browser->is_app());
 
-  browser->tab_strip_model()->RemoveObserver(this);
-
   if (browser_to_app_id_map_.find(browser) != browser_to_app_id_map_.end()) {
     launcher_controller_->UnlockV1AppWithID(browser_to_app_id_map_[browser]);
     browser_to_app_id_map_.erase(browser);