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 0dc58c7a66de814403a1c0ac66f649707a117531..a3cdfc8bcae6a8b82e07f83a38f253ae17545dcb 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -66,6 +66,7 @@
 #include "chrome/browser/ui/views/extensions/bookmark_app_confirmation_view.h"
 #include "chrome/browser/ui/views/extensions/extension_keybinding_registry_views.h"
 #include "chrome/browser/ui/views/find_bar_host.h"
+#include "chrome/browser/ui/views/frame/browser_view_histogram_helper.h"
 #include "chrome/browser/ui/views/frame/browser_view_layout.h"
 #include "chrome/browser/ui/views/frame/browser_view_layout_delegate.h"
 #include "chrome/browser/ui/views/frame/contents_layout_manager.h"
@@ -417,8 +418,8 @@ 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
@@ -1983,6 +1984,11 @@ 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();
 }