Add UMA for first app list paint on Windows.

ui/app_list/views/app_list_view.cc

Index: ui/app_list/views/app_list_view.cc
diff --git a/ui/app_list/views/app_list_view.cc b/ui/app_list/views/app_list_view.cc
index 118ab2b3409271a6c4a0a2e67a021d8b95b05c70..71bca1a6812b081f12c3df0bced4075b865f8fdd 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -4,6 +4,7 @@
 
 #include "ui/app_list/views/app_list_view.h"
 
+#include "base/callback.h"
 #include "base/command_line.h"
 #include "base/strings/string_util.h"
 #include "ui/app_list/app_list_constants.h"
@@ -37,6 +38,8 @@ namespace app_list {
 
 namespace {
 
+base::Closure g_next_paint_callback;
+
 // The distance between the arrow tip and edge of the anchor view.
 const int kArrowOffset = 10;
 
@@ -166,6 +169,14 @@ gfx::Size AppListView::GetPreferredSize() {
   return app_list_main_view_->GetPreferredSize();
 }
 
+void AppListView::Paint(gfx::Canvas* canvas) {
+  views::BubbleDelegateView::Paint(canvas);
+  if (!g_next_paint_callback.is_null()) {
+    g_next_paint_callback.Run();
+    g_next_paint_callback = base::Closure();

[benwells, 2013/08/21 04:54:09]

Should this be g_next_paint_callback.Reset()?

[koz (OOO until 15th September), 2013/08/21 06:54:32]

Done.

+  }
+}
+
 bool AppListView::ShouldHandleSystemCommands() const {
   return true;
 }
@@ -183,6 +194,11 @@ void AppListView::OnSigninStatusChanged() {
   app_list_main_view_->search_box_view()->InvalidateMenu();
 }
 
+// static
+void AppListView::SetAppListNextPaintCallback(const base::Closure& callback) {
+  g_next_paint_callback = callback;
+}
+
 #if defined(OS_WIN)
 HWND AppListView::GetHWND() const {
 #if defined(USE_AURA)