Add Startup.BrowserView.FirstPaint / .CompositingEnded histograms.

chrome/browser/ui/views/frame/browser_view.cc

Index: chrome/browser/ui/views/frame/browser_view.cc
diff --git a/chrome/browser/ui/views/frame/browser_view.cc b/chrome/browser/ui/views/frame/browser_view.cc
index 4d3c09b477956c13a90c0dd7994103300574c09c..f614c24070c12e8a7b07dafc6e7874cba74cfc8c 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -419,8 +419,7 @@ BrowserView::BrowserView()
       handling_theme_changed_(false),
       in_process_fullscreen_(false),
       force_location_bar_focus_(false),
-      activate_modal_dialog_factory_(this) {
-}
+      activate_modal_dialog_factory_(this) {}
 
 BrowserView::~BrowserView() {
   // All the tabs should have been destroyed already. If we were closed by the
@@ -2000,6 +1999,16 @@ void BrowserView::ViewHierarchyChanged(
   }
 }
 
+void BrowserView::PaintChildren(const ui::PaintContext& context) {
+  views::ClientView::PaintChildren(context);
+  // Don't reset the instance before it had a chance to get compositor callback.
+  if (!histogram_helper_) {
+    histogram_helper_ = BrowserWindowHistogramHelper::
+        MaybeRecordValueAndCreateInstanceOnBrowserPaint(
+            GetWidget()->GetCompositor());
+  }
+}
+
 void BrowserView::ChildPreferredSizeChanged(View* child) {
   Layout();
 }