Add UMA for first app list paint on Windows.

chrome/browser/ui/views/app_list/app_list_controller_win.cc

Index: chrome/browser/ui/views/app_list/app_list_controller_win.cc
diff --git a/chrome/browser/ui/views/app_list/app_list_controller_win.cc b/chrome/browser/ui/views/app_list/app_list_controller_win.cc
index 759c5d7f37d4e6f0bb60b631e3562b62bde15bca..2574a61b48891eff8499c12630faa2ec18a975b3 100644
--- a/chrome/browser/ui/views/app_list/app_list_controller_win.cc
+++ b/chrome/browser/ui/views/app_list/app_list_controller_win.cc
@@ -795,6 +795,8 @@ class AppListController : public AppListServiceImpl {
   void OnAppListClosing();
 
   // AppListService overrides:
+  virtual void SetAppListNextPaintCallback(
+      const base::Closure& callback) OVERRIDE;
   virtual void HandleFirstRun() OVERRIDE;
   virtual void Init(Profile* initial_profile) OVERRIDE;
   virtual void CreateForProfile(Profile* requested_profile) OVERRIDE;
@@ -970,6 +972,11 @@ void AppListController::OnLoadProfileForWarmup(Profile* initial_profile) {
   shower_->WarmupForProfile(initial_profile);
 }
 
+void AppListController::SetAppListNextPaintCallback(
+    const base::Closure& callback) {
+  app_list::AppListView::SetNextPaintCallback(callback);
+}
+
 void AppListController::HandleFirstRun() {
   PrefService* local_state = g_browser_process->local_state();
   // If the app list is already enabled during first run, then the user had