Add histogram for how tab closing time. Did some cleanup along the way.

chrome/test/startup/feature_startup_test.cc

 // Copyright (c) 2006-2008 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 "base/file_util.h"
 #include "base/gfx/rect.h"
 #include "base/path_service.h"
 #include "base/perftimer.h"
 #include "base/string_util.h"
 #include "base/time.h"
@@ skipping 116 matching lines @@
       ASSERT_TRUE(window->GetTabCount(&tab_count));
       ASSERT_EQ(1, tab_count);
 
       // Hit ctl-t and wait for the tab to load.
       window->ApplyAccelerator(IDC_NEW_TAB);
       ASSERT_TRUE(window->WaitForTabCountToBecome(2, 5000));
       int duration;
       ASSERT_TRUE(automation()->WaitForInitialNewTabUILoad(&duration));
 
       // Collect the timing information.
-      ASSERT_TRUE(automation()->GetMetricEventDuration("NewTab.ScriptStart",
+      ASSERT_TRUE(automation()->GetMetricEventDuration("Tab.NewTabScriptStart",
           &duration));
       scriptstart_times[i] = TimeDelta::FromMilliseconds(duration);
 
       ASSERT_TRUE(automation()->GetMetricEventDuration(
-          "NewTab.DOMContentLoaded", &duration));
+          "Tab.NewTabDOMContentLoaded", &duration));
       domcontentloaded_times[i] = TimeDelta::FromMilliseconds(duration);
 
-      ASSERT_TRUE(automation()->GetMetricEventDuration("NewTab.Onload",
+      ASSERT_TRUE(automation()->GetMetricEventDuration("Tab.NewTabOnload",
           &duration));
       onload_times[i] = TimeDelta::FromMilliseconds(duration);
 
       window = NULL;
       UITest::TearDown();
     }
 
     PrintTimings("script_start", scriptstart_times, false /* important */);
     PrintTimings("domcontent_loaded", domcontentloaded_times,
                  false /* important */);
@@ skipping 36 matching lines @@
 }
 
 TEST_F(NewTabUIStartupTest, NativeFrameGtkThemeCold) {
   RunStartupTest("tab_custom_frame_gtk_theme_cold", false /* cold */,
                  false /* not important */,
                  UITest::CUSTOM_FRAME_NATIVE_THEME);
 }
 #endif
 
 }  // namespace