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 e4d96a2b4916d8c07350944377ddef19bcdbeecc..4563e49fedd9ad108edf0a5240fd5771a15fe228 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -52,6 +52,7 @@
 #include "chrome/browser/ui/browser_dialogs.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_list.h"
+#include "chrome/browser/ui/browser_view_histogram_helper.h"
 #include "chrome/browser/ui/browser_window_state.h"
 #include "chrome/browser/ui/sync/bubble_sync_promo_delegate.h"
 #include "chrome/browser/ui/tabs/tab_menu_model.h"
@@ -418,8 +419,8 @@ BrowserView::BrowserView()
       handling_theme_changed_(false),
       in_process_fullscreen_(false),
       force_location_bar_focus_(false),
-      activate_modal_dialog_factory_(this) {
-}
+      histogram_helper_(base::MakeUnique<BrowserViewHistogramHelper>()),
+      activate_modal_dialog_factory_(this) {}
 
 BrowserView::~BrowserView() {
   // All the tabs should have been destroyed already. If we were closed by the
@@ -1995,6 +1996,11 @@ void BrowserView::ViewHierarchyChanged(
   }
 }
 
+void BrowserView::PaintChildren(const ui::PaintContext& context) {
+  views::ClientView::PaintChildren(context);
+  histogram_helper_->OnDidPaintChildren(GetWidget()->GetCompositor());
+}
+
 void BrowserView::ChildPreferredSizeChanged(View* child) {
   Layout();
 }