GTK: Add TRACE_EVENTs around gtk ui events.

chrome/browser/ui/gtk/tabs/dragged_view_gtk.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/gtk/tabs/dragged_view_gtk.h"
 
 #include <gdk/gdk.h>
 
 #include <algorithm>
 
+#include "base/debug/trace_event.h"
 #include "base/i18n/rtl.h"
 #include "base/stl_util.h"
 #include "chrome/browser/extensions/extension_tab_helper.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/tabs/tab_strip_model.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/ui/gtk/gtk_theme_service.h"
 #include "chrome/browser/ui/gtk/gtk_util.h"
 #include "chrome/browser/ui/gtk/tabs/drag_data.h"
@@ skipping 343 matching lines @@
   }
 
   cairo_destroy(cairo_context);
 
   // Set the shape mask.
   gdk_window_shape_combine_mask(container_->window, pixmap, 0, 0);
   g_object_unref(pixmap);
 }
 
 gboolean DraggedViewGtk::OnExpose(GtkWidget* widget, GdkEventExpose* event) {
+  TRACE_EVENT0("ui::gtk", "DraggedViewGtk::OnExpose");
+
   if (ui::IsScreenComposited())
     SetContainerTransparency();
   else
     SetContainerShapeMask();
 
   // Only used when not attached.
   int tab_height = static_cast<int>(
       kScalingFactor * renderers_[drag_data_->source_tab_index()]->height());
 
   // Draw the render area.
@@ skipping 65 matching lines @@
     if (!attached_) {
       paint_at = widget_width / kScalingFactor -
           GetWidthInTabStripFromTo(0, index + 1);
     }
   }
 
   cairo_set_source_surface(cr, surface, paint_at, 0);
   cairo_paint(cr);
   cairo_surface_destroy(surface);
 }